To answer the given above, multiply the whole equation with least common multiple of the denominators which is 5n. Shown below,
(4/5n - 1/5 = 2/5n) x 5n
4 - 1(n) = 2
-n = -2, n = 2
The answer is not among the choices, it could have been letter A except that the constant in A is negative.
d = r * t
d/t = r
-35.75 / 3.25 = r
-11 = r
r = -11 ft / min
d = r*t
d = -11 ft/min * 1 min
d = -11 ft
The probe is 11 feet below sea level after 1 minute
B would be 5.40 because inches and yards would be 135