Question

Cassie's sister is 3 times as old as he is. His sister is 21 years old. Let c represent Casey's age. Write and solve the equation you would would use to find Casey's age.

Answer 1

Step-by-step explanation:

Let casey's age be c,

Her sisters age=21

Her sister is three times his age

i.e. 3*c=21

Therefore,c=21/3=7

Hence, Casey is 7 years old.