1.设两人的x,三人y.
可列方程组;x+y=50
35x+25y=1510
把x+y=50乘上25,得25x+25y=1250,
用35x+25y减去25x+25y,1510-1250,得10x=260,x=26,则y=24.
26/2=13,y/3=8.即两人的十三间,三人八间.
2.设甲速x,乙速y.
30(x+y)=400
80(y-x)=400
先化简,得30x+30y=400
80y-80x=400
30x+30y=400乘上8,80y-80x=400乘上3,得
240x+240y=3200(1),240y-240x=1200(2)
(1)+(2),480y=4400.
y=55/6,x=25/6.