SOLUTION: I'd really appreciate your input on this problem. Tom and David both collected a total of 480 marbles. Tom stacked each column with 6 marbles. and David stacked each column wit

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Question 92432: I'd really appreciate your input on this problem.
Tom and David both collected a total of 480 marbles. Tom stacked each column with 6 marbles. and David stacked each column with 9 marbles. They stacked 72 columns together. Write an equation using this information.
Well, i came up with 56 columns for Tom; and 16 columns for David which equal 72 together. Tom collected 56columns x 6marbles=336
David collected 16columns x 9marbles=144
Tom plus David=480marbles. But, how do i write an equation for these numbers??
Answer by scott8148(6628) (Show Source):
You can put this solution on YOUR website!
start by defining variables ... let t=Tom's marbles, let d=David's marbles ... then write equations

"Tom and David both collected a total of 480 marbles" ... t+d=480

"Tom stacked each column with 6 marbles. and David stacked each column with 9 marbles. They stacked 72 columns together" ... (t/6)+(d/9)=72

this gives you two equations and two unknowns ... the easiest solution method is probably substitution