(m+n)/3+(n-m)/4=2 ①
4m+n/3=13 ②
m+7n=24 ③
12m+n=39 ④
12m+84n=288 ⑤
12m+n=39 ⑥
⑤- ⑥得
83n=249
n=3
代入⑥,得m=3
所以:
m=3
n=3
(m+n)/3+n/4-m=2.....(1)
4m+n/3=13..............(2)
(1): 4(m+n)+3n-12m=24
-8m+4n=24
n=2m+6........(3)
(2): 12m+n=39........(4)
(3)代入(4): 12m+2m+6=39
14m=33
m=33/14
n=2*33/14+6=75/7