7x-4y=5 ------------------ 7X = 5 + 4Y --------------- X = (5 + 4Y) /7 ------ ecuación (1)
9x+8y=13 ----------------------------------------------------------------------- ecuación (2)
(1) en (2)
X =
9 (5 + 4Y) /7 + 8y = 13
45 + 36Y
--------- + 8Y = 13
7
45 + 36Y
--------- = 13 - 8Y
7
45 + 36Y = 7 (13 - 8Y)
45 + 36Y = 91 - 56Y
36Y + 56Y = 91 - 45
92Y = 46
Y = 46/92
Y = 1/2
