Juan collected 5 times as many rocks as Will. When Juan gave Will some of his rocks, they each had 15. How many rocks had Juan given to Will?
j = 5w
s = 'some'
j - s = 15 and w + s = 15 sub in 5w = j
5w - s = 15
Add red equations
6w = 30
w = 5 originally he wound up with 15 so juan gave him 10 = 'some'
ANOTHER method.....they both end up with 15 = 30 total
j + w = 30
5w + w = 30
w = 5 then he wound up with 15 so juan gave him 10 = 'some'