Help with algebra question please?

Question

I'm in 10th grade so this should be easy for me but I forgot how to do it :(

It's in my Geometry book and I really need to turn it in tomorrow!!..here it is:

The length of line AC is 45. If AB = x + 8 and BC = 3x - 3, find the value of x.

Answer 1

AB+BC=AC

Plug those values in ------>

x+8+3x-3=AC

4x+5=AC

AC=45

4x+5=45

4x=40

x=10

Answer 2

45+ x+ 8+ 3x-3 = 180 (Degrees in a triangle)

50+ 4x = 180

4x = 130

x= 32.5

Answer 3

45= x+8+3x-3

45=4x+5

40=4x

x=10

Answer 4

you add x+8 and 3x-3 because they equal 45 then u combine 8 and -3 to get 5 and u combine 3x and x so u have 4x. so now it is 4x+5= 45 then you subtract 5 and have 4x=40 then u divide 40 by 4 and get 10 so 10 is ur answer.