因为a+b=35.2所以b=35.2-a把b代入a-b=25.8为a-(35.2-a)=25.8a-35.2+a=25.82a-35.2=25.82a=25.8+35.22a=61a=30.5把a代入a+b=35.2得30.5+b=35.2b=35.2-30.5b=4.7二元一次方程的代入法a×b=30.5×4.7=143.35
143.35 a是30.5 b为4.7 代数法
两式相加2a=61a=30.5,再求b=4.730.5×4.7=143.35