1/(x-1)(x-2) + 1/(x-2)(x-3) + 1/(x-3)(x-4) = 1/6

see below

Step-by-step explanation:

See attached screenshot (too time consuming to type out using latex, so used MS word).

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.

step-by-step explanation: