1) hallar 2x
20 + 30 + x = 90
50 + x = 90
x = 90 - 50
x = 40
2x = 40(2)
2x = 80
2) hallar x
x + x + 4x + x + 10 + x + 10 = 180
8x + 20 = 180
8x = 180 - 20
8x = 160
x = 160/8
x = 20
