{x/60+y/80=10,x/60+y/40=15、{2x/3+3y/4=1/5,5x/6-5y/2=2、{5/2(x+y)=1200,10/3(x+y)=1200

问题描述:

{x/60+y/80=10,x/60+y/40=15、{2x/3+3y/4=1/5,5x/6-5y/2=2、{5/2(x+y)=1200,10/3(x+y)=1200
{4x+5y=98,5y-4x=2、{x/3+y/4=54/60,y/4+x/5=42/60怎么解?
{40-y=x-4 40-y=y-x

x/60+y/80=10,(1)
x/60+y/40=15(2)
(2)-(1) y/80=5 y=400
x/60+400/40=15
x=300