2/7+7/9
=18/63+49/63
=67/63
=1又4/63
1-（5/9-3/8）
=1-13/72
=59/7224乘17分之12等于？ 8分之1加0.375等于？24×12/17
=288/17
=16又16/17

1/8+0.375
=1/8+3/8
=1/2最后一题0.75加12分之5等于？0.75+5/12
=3/4+5/12
=7/6
=1又1/6