甲乙两车共运一堆煤,运完时,甲车运了总数的7/15多12吨乙运的是甲的1/2,
设这堆煤共有x吨
(7x/15 + 12 ) (1+1/2) = x
7x /15 +12 = 2x /3
7x + 15x12 = 10x
3x = 15x12
x = 5x12 = 60 吨