Question

This month john spent 120 minutes calling on the phone. This is 20% less than the last month. How many minutes did he spend on the phone last month?

Answer 1

150 minutes

Explanation:

20% less is (100 - 20)% = 80% =
`(80)/(100)` = 0.8

time spent on phone last month =
`(120)/(0.8)` = 150 minutes

Answer 2

120 x 10 =1200

120 x 10 =1200

1200+1200=2400

Last month he used 2400 minutes