word problems

Question

Four brothers in one family have a combined age of 39 years.

 

Alan is three times Colin's age, Bill is 6 years younger than Alan and Don is a quarter of Bill's age.

 

How old are each of the four brothers?

 

Answer 1

Let A = Alan, B = Bill, C = Colin, and D = Don  ages

 

GIVEN : A = 3*C, A = B + 6 , B = D/4  ,   and   A +B +C +D = 39

 

Just solve the equations:

 

step is to solve the in terms of A so from above:

 

C = A/3,  B = A - 6, and D = 4*B  = 4*(A-6): then replace in the equation: A +B +C +D = 39

 

A + (A-6) + A/3 + 4*(A-6) = 39

 

Solve for A then go back and solve for the rest.