Remember letters can also be used to stand for the unknown numbers in open sentences.

Example 1

Find x, if 6 + x = 10

Solution

6 + x – 6 = 10 – 6

X + (6 – 6) = 4

:. X = 4

Example 2

I think of a number, multiply it by 2 and add 4, the result is 10. Find the number.

Solution

Let the number be y

2y + 4 = 10

2y + 4 – 4 = 10 – 4

2y = 6

:. Y = 6/2 = 3

Home work: Find the value of the letters in the question below

1) x + 2 = 5 (2) 33 + a = 45

3) When 3 is added to a number the result is 15. Find the number

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