Difference in doughnuts = 50 - 40 = 10
Difference in money = 15 + 5 = 20
20 ÷ 10 = $2
Each doughnut costs $2
<em>Check:</em>
40 x 2 + 5 = $85
50 x 2 -15 = $85
Ravi has $85 at first.
Each doughnut costs $2
Let start off with 5/8+7/8= 1 4/8
Now it's 13+1 4/8= 14 4/8 or 14 1/2 :)
Im pretty sure the answer is x=-2