x-(4/5-1/3)=7/30
x-7/15=7/30 …………(被减数=差+减数)
x=7/30+7/15
x=7/10
7/8-(x-1/12)=3/4
x-1/12=7/8-3/4…………(减数=被减数-差)
x-1/12=1/8
x=1/8+1/12
x=5/24
x-(4/5-1/3)=7/30
x-7/15=7/30 …………(被减数=差+减数)
x=7/30+7/15
x=7/10
7/8-(x-1/12)=3/4
x-1/12=7/8-3/4…………(减数=被减数-差)
x-1/12=1/8
x=1/8+1/12
x=5/24