Tìm x,y rồi điền vào chỗ chấm:
x+y: 136, x/y: 1/3, x=..............,y=...........................
x+y: 875, x/y: 2/5, x=...............,y=..........................
x+y: 1160, x/y: 3/5, x=...............,y=..........................
x+y: 540, x/y: 7/5, x=...............,y=..........................