Which of the following problems cannot be solved using a proportion?
A: A map has the scale factor 1 in = 50 miles. If the map shows the distance between Springdale and Anytown to be 2.5 inches, how far apart are the two cities?
B: An 8-foot long wooden plank needs to be cut into 5-inch pieces. How many 5-inch pieces can be cut from the plank?
C:After paying $10 for one phone plan, the charge is $0.15 per minute. How much does a 20-minute phone call cost?
D: In one shop, a pound of specialty candy costs $7.99. How much will 0.75 pound of candy cost?

Question

Which of the following problems cannot be solved using a proportion? 
A: A map has the scale factor 1 in = 50 miles. If the map shows the distance between Springdale and Anytown to be 2.5 inches, how far apart are the two cities? 
B: An 8-foot long wooden plank needs to be cut into 5-inch pieces. How many 5-inch pieces can be cut from the plank? 
C:After paying $10 for one phone plan, the charge is $0.15 per minute. How much does a 20-minute phone call cost? 
D: In one shop, a pound of specialty candy costs $7.99. How much will 0.75 pound of candy cost?