Răspuns:
b) y/x-y = 5/4
4y=5(x-y)
5x-5y = 4y
5x = 9y => x/y = 9/5
c) 3x+y/x+2y = 5/8
8(3x+y) = 5(x + 2y)
24x + 8y = 5x + 10y
24x - 5x = 10y - 8y
19x = 2y => x/y = 2/19
d) 2x+y/5x-2y = 7/9
9(2x+3y) = 7(5x - 2y)
18x + 27y = 35x - 14y
27y + 14y = 35x - 18x
41y = 17x => x/y = 41/17