Multiply the first bracket by -2
Multiply the second bracket by 2
x-3-12+4x= 4x-10
- negative number times + positive number= - negative number
- negative number times -negative number = + positive number
x+ 4x-3-12= 4x-10
5x-15= 4x-10
Move 4x to the other side
5x-4x-15= 4x-4x-10
x-15= -10
Move -15 to the other side
x-15+15= -10+15
x= 5
Answer : x= 5