Answer:
157.5 minutes
Explanation:
We can use ratios to solve
2 lbs 3.5 lbs
--------------- = ----------------
90 minutes x minutes
Using cross products
2x = 3.5 * 90
2x =315
Divide each side by 2
2x/2 = 315/2
x =157.5 minutes
or 2 hours and 37.5 minutes