Question

x+30=
30-20+2x=10
3x-10+13=-2x+28
20x-30=+30-20
-5x+45-89=-90+41
20-80+2x=10
13x-23-45=-7x+12

Answer 1

13x+7x=12+23+45
20x=80
x=80-20
x=60

Answer 2

$13x7x =12 + 23 + 45 \\ 20x = 80 \\ x = 80 - 20 \\ x = 60$