I have a question that ive been stumped on for a while

Question

One yardstick for measuring how

steadily —if slowly —athletic performance has improved is the mile run. In 1957​, the local record for the running of a certain distance was 3​ minutes, 59.1 seconds, or 239.1 seconds. In the​ half-century since​ then, the record has decreased by 0.5 seconds per year.

a. Express the record time for the mile​ run, M, as a function of the number of years after 1957 comma x.1957, x.

b. If this trend​ continues, in which year will someone run a​ 3-minute, or​ 180-second, mile?

Answer 1

a. M = 239.1 - 0.5(x - 1957)

b. 180 = 239.1 - 0.5(x - 1957)

180 = 239.1 - 0.5x + 978.5

-1037.6 = -0.5x

2075.2 = x