<PRE><B>Question 1016975</B>
let x be the number of marbles that Mark has and y be the number of marbles Don has, then
1) x + y = 113
2) y = 3x + 1
:
substitute for y in equation 1 using equation 2
:
x + (3x + 1) = 113
:
4x = 112
:
x = 28
:
Mark has 28 marbles and Don has 85 marbles
:
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