Question

You drive 70 miles per hour but then slow your speed by 15 miles per hour. You then return to your speed of 70 miles per hour. Which expression shows how your speed changed?

Answer 1

Driving 70 miles per hour.
Slow your speed means decrease in speed=
70+(-15)=70-15=55 miles/ hr
And then return to speed of 70 miles/hr means
add 15 miles to the speed.
We get
70+(-15)+15 =70 miles / hr