Question

A school record in a certain race in 1960 was 3.8 minutes. In 1980 the school record in the same event was 3.65 minutes

Answer 1

it would be b.
from 1960 to 1980 the time decrease by 0.15 minutes, so slope would be
−(0.15/20)=−0.0075

as b is the only equation with negative slope, it has to be the right one.
Also you could just insert the numbers (x=year)
if x=1960 then:
−0.0075∗1960+18.5=−14.7+18.5=3.8

if x=1980 then
−0.0075∗1980+18.5=−14.85+18.5=3.65