The easiest way to solve when computing problems of this type is to rewrite the statement in equation form. On one side of the equation is the fraction of 4 miles per 1 inch. On the other side is the fraction of the unknown miles traveled per the measured inches.
Take note that all the mile values are written as numerators and all the inch values are written as denominators.
miles traveled = 4 \u00D7 314.5 = 1258 miles
For the round-trip distance, multiply the 1-way distance by 2:
1258 \u00D7 2 = 2516 miles