Don L. answered • 01/31/16
Tutor
5
(18)
Fifteen years teaching and tutoring basic math skills and algebra
Hi Sarai, let x be the amount Max started with. We can set up an equation to represent what he spent and what he had left.
On day 1, Max spent 1 / 2 of his money or 1 / 2 * x.
On day 2, Max spent 2 / 5 of the money he had left, or 2 / 5 * 1 / 2 * x.
On day 3, Max spent his remaining 15.
Equation:
x - (1 / 2 * x) - (2 / 5 * 1 / 2 * x) = 15
x - (1 / 2 * x) - (1 / 5 * x) = 15
Multiply all terms by 10 to clear the fractions:
10x - 5x - 2x = 150
3x = 150
Divide both sides by 3:
x = 50
Max started with 50 dollars.
On day one, he spend 1 / 2 of his money, or 25 dollars. This left him with 25 dollars.
On day two, he spent 2 / 5 of his remaining money, or 10 dollars. This left him with 15 dollars.
On day three, he spent his remaining 15 dollars.
Questions?
