Question 19721
1) x+4=-1:
x+4-4=-1-4
x=-5

2) 5b=-25:
{{{5b/5}}}={{{-25/5}}}
b=-5

3) 3x+4=13: 
3x+4-4=13-4
3x=9
{{{3x/3}}}={{{9/3}}}
x=3

4) 5(x-2)=15: 
5x-10=15
5x-10+10=15+10
5x=25
{{{5x/5=25/5}}}
x=5

5) x+8=3(x-4)
x+8=3x-12
x+8-x=3x-12-x
8=2x-12
8+12=2x-12+12
20=2x
{{{20/2}}}={{{2x/2}}}
10=x
hope you understand all of them
=)