Answer:
4) x = 11
5) x = -6
6) x = 18
7) x = 21
Step-by-step explanation:
(the equations and the answers are bolded)
4)
x + 9 = 21
subtract 9 from both sides of the equation
x + 9 - 9 = 21 - 9
x = 21 - 9
x = 11
5)
21 - x = 27
add x to both sides
21 - x + x = 27 + x
21 = 27 + x
subtract 27 from both sides
21 - 27 = 27 - 27 + x
-6 = x
6)
21 = x + 3
subtract 3 from both sides
21 - 3 = x + 3 - 3
21 - 3 = x
21 - 3 = 18
18 = x
7)
x - 9 = 12
add 9 to both sides
x - 9 + 9 = 12 + 9
x = 12 + 9
x = 21
