Răspuns:
Explicație pas cu pas:
(x + 1)/2 = 6/3
3(x + 1) = 2*6
3x + 3 = 12
3x = 12 - 3 = 9
x = 9 : 3 = 3
_________________
13/21 = (10x - 21)/(8x - 16)
13(8x - 16) = 21(10x - 21)
104x - 208 = 210x - 441
441 - 208 = 210x - 104x
233 = 106x
x = 233/106
___________________
x/y = 7/9
x = 7y/9
5x + 2y = 35y/9 + 18y/9 = 53y/9
2x - y = 14y/9 - 9y/9 = 5y/9
(5x + 2y)/(2x - y) = 53y/9 : 5y/9 = 53y/9 * 9/5y = 53/5