Which fraction is bigger?
13/20 or 5/8

13/20 because it is 6.5 vs 5/8 being 6.25

13/20 would be the same as 65%.  Divide 13 by 20 to get 65%.  Then 5/8 would be the same as 62.5%.  Divide 5 by 8.  The reason I do it this way is because you could spend all day multiplying the fractions to higher numbers and see which is bigger, but converting to other forms is the best to tell.  Percentages don't lie. So that means that 13/20 is bigger. 

3x - 8 = -2

3x -8+8 = -2 +8

3x = 6

3x/3 = 6/3

x = 2

s

x - 6

( 2-6)

= -4

that is the value of x -6

= -4