Respuesta :
find first common multiplule
factor them
9=3*3
21=3*7
lcm=3*3*7=63
63 times 2=126
63 times 3=189
the first common multipules are 63,126,189
factor them
9=3*3
21=3*7
lcm=3*3*7=63
63 times 2=126
63 times 3=189
the first common multipules are 63,126,189