(a.): for what amount of driving do the two plans cost the same? (b.): what is the cost when the two plans cost the same time?

First plan: 53 + 0.08m

Second plan: 46 + 0.12m

____________________________________________________________

Make the two plans equal to each other & solve.

53 + 0.08m = 46 + 0.12m

Subtract 46 from both sides.

7 = 0.04m

Divide both sides by 0.04.

m = 175

Driving 175 miles would make the two plans cost the same.

Plug 175 into either one of the plans. We'll plug 175 for m into both just to double check :)

First plan: 53 + 0.08m ⇒ 53 + 0.08(175) = 67

Second plan: 46 + 0.12m ⇒ 46 + 0.12(175) = 67

The cost when the two plans cost the same is $67.

the answer is d. 75%