Set up an equation and solve it to find the unknown number:
3 is added to three-fourth of a number to get 21. [3 marks]

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Solution

Let the number be z. [0.5 mark]
According to the question, $3 + \frac{3}{4} z = 21$ [1 mark]
$\Rightarrow \frac{3}{4} z = 21 - 3 \Rightarrow \frac{3 z}{4} = 18 [0.5 m a r k] \Rightarrow 3 z = 18 \times 4 \Rightarrow 3 z = 72 [0.5 m a r k] \Rightarrow z = \frac{72}{3} \Rightarrow z = 24 [0.5 m a r k]$

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Q. Question 1(c)
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Set up an equation and solve it to find the unknown number: 3 is added to three-fourth of a number to get 21. [3 marks]

Let the number be z. [0.5 mark] According to the question, 3+34z=21 [1 mark] ⇒34z=21−3⇒3z4=18 [0.5mark]⇒3z=18×4⇒3z=72 [0.5mark] ⇒z=723⇒z=24 [0.5mark]

Set up an equation and solve it to find the unknown number:
3 is added to three-fourth of a number to get 21. [3 marks]