marissa earned $560 in the summer. she earned $40 each week for part of the summer and $60 each week for the rest. If she earned $40 each week twice as often as she earned $60, how many weeks did she earn $40?
80x+60x=560
140x=560
X=4
4*2=8 so Marissa earned $40 a week for 8 weeks
She earned $40 each week twice as often as she earned $60.
Let us say she earned $60 for x weeks.
Therefore $40 was for 2x weeks.
Her total = $560.
40(2x) + 60(x) = 560
80x + 60x = 560
140x = 560
x = 560 / 140 = 4
x = 4 weeks.
But $40 was for 2x weeks.
= 2*(4) = 8.
$40 was for 8 weeks.