The cost, c , of a health club membership is related linearly to its length in months, m If a 12 -month membership costs 260 dollars and an 18 -month membership costs 380 dollars , which equation can be used to find the cost of a 30 -month membership?
Answer
A
c minus 380 is equal to 20 times open paren 30 minus 18 close paren
B
c minus 380 is equal to 1 over 20 times open paren 30 minus 18 close paren
C
c minus 18 is equal to 20 times open paren 380 minus 30 close paren
D
c minus 18 is equal to 20 times open paren 30 minus 12 close paren
Explanation
The cost increases by $380 − $260 = $120 over 18 − 12 = 6 months, so the rate is $120 ÷ 6 = $20 per month. Using the known point (18, 380), the equation for a 30-month membership is c − 380 = 20(30 − 18). This is choice A.
AI-written and checked against the verified answer.