Question

An equation is shown below:

Answer 1

First step
5.(2x-8)
= (5.2x) + (5. (-8) )
=10x + (-45)
note :(+) . (-) = (-)
so + (-45)= (-45)


Add 15 to this equation 
= 10x -40 +15= -15
=10x -25= -15
Leave x alone and make it positive
By the way, if you put (-25) in the right term, this number's notation (I mean -) will change 
Namely
= 10x= (-15)+25
=10x= 10
x=1

Hope it helps :)
P.s. I dont know mathematical terms that's why i couldn't explain it properly but i tried to help as far as i can :)