Choice B is the correct answer. When traveling in the same direction, the faster car pulls ahead.

Let $t$ = time in hours.

Analysis: The difference in distances equals 45 miles: $70t - 55t = 45$$15t = 45$$t = 3$

Solution: 3 hours

Verification: After 3 hours:

• Car A: $55(3) = 165$ miles
• Car B: $70(3) = 210$ miles
• Difference: $210 - 165 = 45$ miles ✓

💡 Strategic Tip: Same direction → subtract speeds to find rate of separation.

Choice A is incorrect because $70(2) - 55(2) = 140 - 110 = 30 \ eq 45$.

Choice C is incorrect because $70(4) - 55(4) = 280 - 220 = 60 \ eq 45$.

Choice D is incorrect because $70(5) - 55(5) = 350 - 275 = 75 \ eq 45$.