Answer:
13. 6
14. -2
15. 3/5
16. -3
17. 24
18. 4
19. 7
20. 0.80
21. 5.5
Explanation:
13. 4x-20=4
4x=20+4
x=24/4
x=6
14. 9x + 17 = -1
9x = -1 + -17
x = -18 / 9
x = -2
15. 2x-12 = 7x - 15
2x = 7x -15+12
2x = 7x -3
2x-7x = -3
-5x = -3
x= -3/-5
Note: The minus will cancel themselves out
x= 3/5
16. 6x + 10 = x-5
6x = x - 5 - 10
6x-x = -15
5x = -15
x = -15 / 5
x = -3
17. x+6 *4 = 44
x + 20 = 44
x = 44 - 20
x = 24
18. (x - 1) + x + 5 = 12
x - 1 + x = 12 - 5
X - 1 + x = 7
x + x = 7 + 1
2x = 8
x = 8/2
x = 4
19. 2(3x - 9 + x) = 38
6x - 18 + 2x = 38
6x + 2x = 56
8x = 56
x = 56/8
x = 7
20. 12/ 0.80 = 15 Units
21. 6x + 6*4 = 4x * 9
6x + 6 = 4x * 9/4
6x - 4x + 6 = 9/4
6x = 4x - 11
6x - 4x = - 11
2x = -11
x = -11/2
x= -5.5