Hailey's Income Is $40 Per Week

Multiple Choice

Hailey's income is $40 per week.She spends all of it on coffee (C) and doughnuts (D) .Coffee costs $2 per cup and doughnuts cost $1 each.Her marginal rate of substitution for coffee with doughnuts is D/C.How many cups of coffee and how many doughnuts will she purchase each week?

A) 15 cups of coffee and 10 doughnuts
B) 10 cups of coffee and 20 doughnuts
C) 20 cups of coffee and 10 doughnuts
D) 5 cups of coffee and 30 doughnuts