Question

He cost, c, of a health club membership is related linearly to its length in months, m. If a 12-month membership costs $260 and an 18-month membership costs $380, which equation can be used to find the cost of a 30-month membership?

A) c - 380 = 1/20(30-18)
B) c - 18 = 20(380-30)
C) c - 380 = 20(30-18)
D) c - 18 = 20(30-12)

Answer 1

The answer is c

Explanation:

got it right on edge

Answer 2

Treat the c formula as a line. c = sm +b; where m= number of months.

using the two examples:

260 = 12s +b
380 = 18s + b
solve for s & b:
s = 20
b =20

So a 30-month membership is:

c = 20(30) + 20 = 600

Solve C for c and you get 600