b) Solve 3 x + 4 = 10.
1 1 1 1
1 1 1 1 1 1 1 1 1 1
3 4 x
x x x
10
3 x + 4
=
10
The scale is balanced.
First, remove the same number of unit cubes from both sides. The scale stays balanced.
1 1 1 1
1 1 1 1
1 1 1 1 1 1
x x x
1 1 1 1 1 1
x x x
3 x + 4 – 4
=
10 – 4
3 x
=
6
1 1
1 1
1 1
x x x
Then, divide each side by 3 to find the value of x .
3 x ÷ 3
=
6 ÷ 3
1 1
x
x
=
2
The scale remains balanced.
x = 2 is a solution of 3 x + 4 = 10.
Check: When x = 2 , 3 x + 4 = 3 × 2 + 4 = 6 + 4 = 10 ✓
10
ISBN 978-981-09-0495-1
Student Handbook, page 35
Grade 7 I Teacher’s Guide 39
G7_Math_PE_WK1-3 004-067.indd 27
7/23/18 9:57 AM
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