4a-3b=27 2a+2b=68 a= b=

4a-3b=27 2a+2b=68 a= b=
4a-3b=27 2a+2b=68 a= b=

4a-3b=27 2a+2b=68 a= b=
因为4a+4b=136
4a-3b=27
所以4b+3b=136-27
b=109/7
a=129/7

4a-3b=27(1)
2a+2b=68 4a+4b=136(2)
(2)-(1)=7b=109 b=109/7
2a+2b=68

2a=68-218/7 2a=258/7 a=129/7