Question

Carlo drove for 3 hours in a fog, then increased his speed by 30 miles per hour (mph) and drove 6 more hours. If his total trip was 540 miles, then what was his speed in the fog.

Answer 1

Let x = the mph for the first three hours.

540 = 3x + 6(x + 30)

540 = 9x + 180

360 = 9x

40 = x