(-24)÷6÷(-16/18)÷15/12 =4÷(8/9)÷15÷12 =9/2×1/15×1/12=1/40
(-24)÷6÷(-16/18)÷15/12
=+(24/6×9/2×4/5)←【这步有错】
=24/6×9/8×4/5
=18/5