{2M+9N=4.8,3M-5N=-15,

问题描述:

{2M+9N=4.8,3M-5N=-15,

{2M+9N=4.8(1)
3M-5N=-15(2)
(1)×3得6m+27n=14.4(3)
(2)×2得 6m-10n=-30 (4)
(3)-(4)37n=44.4
n=1.2
代入(1)得2m+10.8=4.8
m=-3