Algebra
posted by Anonymous on .
Fido gets 2 doggy treats every time he sits and 4 doggy treats every time he rolls over. Throughout the week, he has sat 6 times as often as he has rolled over. In total, he has earned 80 doggy treats. How many times has Fido rolled over??

2 s + 4 r = 80
but s = 6 r
so
16 r = 80
r = 5