Question

usando o metodo da substituição
{x+y=360
{x-y=140

Answer 1

x + y = 360
x - y = 140 ⇒ x = 140 + y

140 + y + y = 360
2y = 360 - 140
2y = 220
y = 220/2
y = 110

x = 140 + y
x = 140 + 110
x = 250

Answer 2

x=360-y

360-y-y=140
360-2y=140
-2y=140-360
-2y=-220
y=110

x=250
y=110