A:3
B:1
C:13
D:-12
She work out that maths problem ____ (correct).
甲、乙两列火车从A、B两地同时出发相向而行,甲车每小时行75千米,乙车每小时行90千米,经过3.5小时两车相遇,A、B两地铁路长多少千米?