Question

Claudia's father is 7 times as old as Claudia. 20 years from now, Claudia will be 1/2 as old as her father. How old is Claudia's father?

Answer 1

Lets label the variables...
x=Claudia's age now
y=Claudia's dad's age now


Lets write a system...
7x=y (7 of Claudia's age are equivalent 1 of her father's)
x+20=$\frac{y}{2}$ (Claudia plus 20 years is equal to half of Claudia's father's age now)

Now solve the system using the elimination of substitution method.
Hope that helps :)