Please help! The monthly cost (in dollars) of water use is a linear function of the amount of water used (in hundreds of cubic feet, HCF). The cost for using 18 HCF of water is $35.02, and the cost for using 52 HCF is $91.12. What is the cost for using 47 HCF of water?

(18,38.98),(29,58.23)

slope = (58.23 - 38.98) / (29 - 18) = 19.25 / 11 = 1.75

y = mx + b

slope(m) = 1.75

use either of ur points...(18,38.98)...x = 18 and y = 38.98

now sub and find b, the y int

38.98 = 1.75(18) + b

38.98 = 31.5 + b

38.98 - 31.5 = b

7.48 = b

so ur equation is : y = 1.75x + 7.48...where x is the amount of water used and y is the monthly cost

so the cost for 23 hcfsub in 23 for x

y = 1.75x + 7.48

y = 1.75(23) + 7.48

y = 40.25 + 7.48

y = $ 47.73 < ur answer

the answer is  

a.

4,624π mm2

step-by-step explanation: