Use the information to find a linerar algebraic equation mod

Use the information to find a linerar algebraic equation model that can be sued to anwser the question: Mark and DOn are planning to sell each of the marble collections at a garage sale. If Don has 3 more than 3 times the number of marbles Mark has, how many does each boy have to sell if the total number of marbles is 59?

Solution

let the number of marbles Mark has be x

==> Don has 3 more than 3 times of x = 3x +3

Total number of marbles = 59

==> x + 3x + 3 = 59

==> 4x = 56

==> x = 56/4

==> x = 14

==> Don has 3(14) +3 = 45

Hence Mark has 14 marbles and Don has 45 marbles.