Question

Suresh played 80 hours of tennis last week. This week Suresh played 50% less tennis. How many hours of tennis did Suresh play this week?

Answer 1

Suresh played 40 hours of tennis this week

Explanation:

The formula for determining the percentage change or rate of change is:

`p = (N - O)/O * 100` Where:

`p` is the percentage change: -50 for this problem
`N` is the New Value: what we will solve for in this problem
`O` is the Old Value: 80 hours for this problem

Substituting and solving for `N` gives:

`-50 = (N - 80)/80 *100`

`color(blue)(80)/color(red)(100) xx -50 = color(blue)(80)/color(red)(100) xx (N - 80)/80 *100`

`-4000/color(red)(100) = cancel(color(blue)(80))/cancel(color(red)(100)) xx (N - 80)/color(blue)(cancel(color(black)(80))) *color(red)(cancel(color(black)(100)))`

`-40 = N - 80`

`-40 + color(red)(80) = N - 80 + color(red)(80)`

`40 = N - 0`

`40 = N`

`N = 40`