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Question
Set up equation and solve them to find the unknown number in the following case:
If I take three-fourths of a number and add 3 to it, I get 21.
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Solution
Let the number be x
Three-fourth of this number = `(3x)/4`
`3/4x + 3 = 21`
`3/4x` = 18 ...(Transposing 3 to R.H.S)
Multiplying both sides by 4
`(3x xx 4)/4`
= 18 × 4
3x = 72
Dividing both sides by 3,
`(3x)/3 = 72/3`
x = 24
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