Question 54527
Let Johns's age = J; Let his brother's age = B
:
Write an equation for each sentence, (the word "is" usually means =)
:
"John's age is four less than six times his brother's age"
 J = (6 * B) - 4
or just write it:
 J = (6B - 4)
:
:
" the sum of their ages is equal to ten."
  J + B = 10
:
In the 1st equation it says J = (6B-4) so substitute that for J in the 2nd eq:
  (6B-4) + B = 10
   6B - 4 + B = 10
           7B = 10 + 4
           7B = 14
            B = 14/7
            B = 2
:
Find out John's age with the 2nd equation:
    J + 2 = 10
        J = 10-2
        J = 8
:
Check our solution in the 1st equation: 6(2) - 4 does indeed = John's age!