Question

A freight train completes its journey of 150 miles 1 hour earlier if its original speed is increased by 5 miles/hour. Give the original speed of the train. a. 20 miles/hour b. 25 miles/hour c. 30 miles/hour d. 35 miles/hour

Answer 1

150(x+5)-150x=x(x+5)
150x+750-150x=x^2+5x
x^2+5x-750=0
(x-25)(x+30)=0
x=25

Answer 2

The answer is B

If we assign speed  variable x; and time variable y; then;

xy=150

(y-1) (x+5) = 150

xy + 5y  - x – 5 = 150

(remember xy = 150), therefore;

5y – x = 5

X = 25

Y = 6