College Algebra word problem

Question

Mark and Don are planning to sell each of their marble collections at a garage sale. If Don has 4 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 76?

Answer 1

Let m be the number of marbles owned by Mark and similarly let d be the number of marbles owned by Don. The problem states that the total number owned by Mark and Don is 76. So the first equation is

m + d = 76

The problem also states that the number owned by Don is 4 more than 3 times that owned by Mark. Algebraically, this can be represented as

d = 3m + 4

Substituting this value of d into the first equation above will allow you to solve for m. Once you know m, and since we know the total owned between them (76), you will easily be able to find the number owned by Don.