1.m+n/3=13,2.m/3-n/4=3,由1式得n=(13-m)*3.把n=（13-m）*3=39-3m代入2式m/3-n/4=3得m/3-（39-3m）/4=3.两边同时乘以12得,4m-117+9m=36,解得m=153/13,所以n=48/13