1) Debbie bought 8 oranges and 7 apples for $10.20. Katrina bought 5 oranges and 14 apples for $12.15. How much did one apple and one orange cost?



2) Joel and Janie are selling fruit. Joel sold 2 small boxes of fruit and 5 large boxes for $31. Janie sold 4 small boxes of fruit and 7 large boxes for $47. How much does one small box of fruit and one large box of fruit cost?



3) Carmen is trying to decide which jet ski rental plan to use. Plan A charges a one-time fee of $40 and $25 per hour. Plan B charges a one-time fee of $60 and $15 per hour. After how many hours will the plans cost the same?



4) Julie and Wendi purchased cell phones. Julie’s phone cost $50 and she pays $0.35 per minute. Wendi’s phone cost $70 and she pays $0.15 per minute. After how many minutes of use will Julie’s phone cost more than Wendi’s?



5) 78 students went on a field trip. They went by van or car. The total number of cars and vans were 10. Each car held 5 students and each van held 12 students. How many cars and how many vans went on the field trip?



6) 168 students went on a field trip. They took a total of 10 vans and buses. Each bus held 42 students, and each van held 6 students. How many vans went on the field trip?



7) Christina spent $81.25 on books. Comic books cost $2.25 each and novels cost $7.00 each. If she bought 15 books, how many comic books did she buy?


8) Tina bought 8 pieces of clothing for a total of $164. Jeans cost $22 each and shirts cost $18 each. How many shirts did Tina buy?


9) Farmer Brown had 25 cows and chickens. They had a total of 72 legs. How many cows and how many chickens did Farmer Brown have?




10) Farmer Brown had 28 cows and chickens. They had a total of 96 legs. How many cows and how many chickens did Farmer Brown have?

What you need to do:

Please WRITE both equations for each problem, identify what your variables represent, and solve the system.

I don’t know what to do, so please help me understand by explaining how you got the answer.
I WANT TO LEARN FROM YOU! :)
- Will give BRAINLIEST -


Don’t answer if you are just going to put a link.

Respuesta :

Hey there

Question no.1:

Debbie bought 8 oranges and 7 apples for $10.20. Katrina bought 5 oranges and 14 apples for $12.15. How much did one apple and one orange cost?

Solution:

Let the cost of one apple be "y" and the cost of one orange be "x".

Here,

According to question,

8x + 7y = $10.20 5x + 14y = $12.15

=> 5(8x + 7y) = 10.20 × 5 => 8(5x + 14y) = 12.15*8

=> 40x + 35y = 51 -->(i) => 40x + 112y = 97.2-->(ii)

By Elimination method,

Equation (i) - (ii)

(40x + 35y) - (40x + 112y) = 51 - 97.2

=> 40x + 35y - 40x - 112y = - 46.2

=> - 77y = - 46.2

=> y = 46.2/77

=> y = 0.6

Putting the value of "y" in equation (i) we get,

40x + 35y = 51

=> 40x + 35 × 0.6 = 51

=> 40x + 21 = 51

=> 40x = 51 - 21

=> 40x = 30

=> x = 0.75

Therefore the cost of one orange is $0.75 and the cost of one apple is $ 0.6.

Question no.2:

Joel and Janie are selling fruit. Joel sold 2 small boxes of fruit and 5 large boxes for $31. Janie sold 4 small boxes of fruit and 7 large boxes for $47. How much does one small box of fruit and one large box of fruit cost?

Solution:

Let the cost of a small box be "x" and the cost of a large box be "y".

Here,

According to question,

2x + 5y = $31 4x + 7y = $47

4(2x + 5y) = 31 × 4 2(4x + 7y) = 47 × 2

=> 8x + 20y = 124 ->(i) => 8x + 14y = 94 ->(ii)

By Elimination method,

Equation (i) - (ii)

(8x + 20y) - (8x + 14y) = 124 - 94

=> 8x + 20y - 8x - 14y = 30

=> 6y = 30

=> y = 30/6

=> y = 5

Putting the value of "y" in Equation (ii) we get,

8x + 14y = 94

=> 8x + 14 × 5 = 94

=> 8x + 70 = 94

=> 8x = 94 - 70

=> 8x = 24

=> x = 24/8

=> x = 3

Therefore, the cost of a small box is $3 and the cost of a large box is $5.