Equations with Variables (Add and Subtract)

How many nines can you see?

Equations with Variables (Add and Subtract)

This Math quiz is called 'Equations with Variables (Add and Subtract)' and it has been written by teachers to help you if you are studying the subject at middle school. Playing educational quizzes is a fabulous way to learn if you are in the 6th, 7th or 8th grade - aged 11 to 14.

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This quiz looks at more complex equations. Examine the following examples.

X - 4 = 8

In order to solve an equation with a variable, we need to make the expressions have the same value. Here, clearly X cannot equal 8 because 8 - 4 would be “4”. So how do we make the “X” equal “8”?

In a variable equation we must either add or subtract the known number in the unknown expression. In the above equation the unknown expression is “X - 4”. As this shows the number “4” is being subtracted from “X” we must add 4 to 4 as follows:

X - 4 + 4

(NOTE: If 4 was being added in the first expression, then we would have to subtract 4 as follows: X + 4 - 4)

We must then do the equal math to the known express of “8” as follows:

8 + 4

The new equation will now look as follows:

X - 4 + 4 = 8 + 4

We now add 8 + 4 = 12 and that makes the value of “X” equal 12.

12 - 4 = 8 so X = 12

1.
X - 132 = 0
264
132
-132
0
X - 132 + 132 = 0 + 132
0 + 132 = 132
132 - 132 = 0
X = 132
2.
X + 83 = 159
242
42
66
76
X + 83 - 83 = 159 - 83
159 - 83 = 76
76 + 83 = 159
X = 76
3.
X + 13 = 54
67
31
41
27
X + 13 - 13 = 54 - 13
54 - 13 = 41
41 + 13 = 54
X = 41
4.
X + 11 = 41
20
52
30
32
X + 11 - 11 = 41 - 11
41 - 11 = 30
30 + 11 = 41
X = 30
5.
X - 14 = 85
81
71
99
89
X - 14 + 14 = 85 + 14
85 + 14 = 99
99 - 14 = 85
X = 99
6.
X - 36 = 61
97
25
87
85
X - 36 + 36 = 61 + 36
61 + 36 = 97
97 - 36 = 61
X = 97
7.
X - 94 = 146
260
240
230
250
X - 94 + 94 = 146 + 94
146 + 94 = 240
240 - 94 = 146
X = 240
8.
X - 67 = 52
119
109
99
17
X - 67 + 67 = 52 + 67
52 + 67 = 119
119 - 67 = 52
X = 119
9.
X + 5 = 33
38
28
27
37
X + 5 - 5 = 33 - 5
33 - 5 = 28
28 + 5 = 33
X = 28
10.
X + 24 = 39
63
5
25
15
X + 24 - 24 = 39 - 24
39 - 24 = 15
15 + 24 = 39
X = 15
Author:  Christine G. Broome

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