Question

The temperature in Chicago was 7 degrees Celsius. It was dropping at a steady rate of 3 degrees per hour. How many hours did it take for the temperature to drop below -5 degrees Celsius?

Write an inequality that represents the situation.

Answer 1

4 hours

Explanation:

Inequality:

`7-3x < -5`

`7-7-3x < -5-7`

`-3x < -12`

`(-3x)/(-3) < (-12)/(-3)`

`x > 4`

Hope this helps

Answer 2

-3x+7 < -5

Explanation:

Lets set x as the number of hours since the time it was 7 degrees.

This means that the expression 7-3x would represent the temperature after x hours.

To find the inequality that represents when it would be below -5 degrees, we just set this less than -5:

-5 > 7-3x.

If you want, you can also rearrange this to -3x+7 < -5.