Let's have Steve's age be x, and his father's age be f Then, we can set up equations Steve is one-fourth as old as his father goes to an equation as x=(1/4)f In five years (x+5), Steve will be one-third as old as his father will be (f+5). This goes to an equation as x+5=(1/3)(f+5) We can then solve the first equation for either variable (I will be doing f), and plug it in for a system of equations.
x=(1/4)f 4x=f ← plug that in for f in the next equation
x+5 = (1/3)(4x+5) ← Solve this for x 3(x+5)=4x+5 3x+15=4x+5 3x+10=4x 10=1x x=10
Therefore, Steve's age is 10. His father's age is f=4x, plug in 10 for x, and his father's age is 40
