Question

If Mary read 2/5 of a page every minute, how long would she take to read 240 pages

Answer 1

First convert 2/5 into a decimal. So divide the numerator by denominator. So 2÷5= 0.4 or 0.40 (both are same). So now divide:
240
÷0.40
--------
600

So, 600 is the answer.

Answer 2

so 2/5 is to 1 minute (that means 2/5:1 not 2/5=1)
240 is to x minute
convert to fraction
(2/5)/1=240/x
multiply both sides by x
(2/5x)/1=240
2x/5=240
multipy both sides by 5 to get rid of fraction
2x=1200
divide by 2
x=600
600 minutes or 10 hours