Question

a)7x=21 b)9x=3 c)5x-2supra lu3=0 d)4x-1supra lu 7=0

Answer 1

$a)\quad 7\text{x} = 21 \Rightarrow \text{x} = \dfrac{21}{7} \Rightarrow \boxed{\text{x} = 3} \\ \\ b) \quad 9\text{x} = 3 \Rightarrow \text{x} = \dfrac{3}{9} \Rightarrow \boxed{\text{x} = \dfrac{1}{3}}\\ \\ c)\quad 5\text{x} - \dfrac{2}{3}=0 \Rightarrow 5\text{x} = \dfrac{2}{3} \Rightarrow\text{x} = \dfrac{\dfrac{2}{3}}{5} \Rightarrow \text{x} = \dfrac{2}{3\cdot 5} \Rightarrow \boxed{\text{x} = \dfrac{2}{15}}$

$d)\quad 4\text{x}-\dfrac{1}{7} = 0 \Rightarrow 4\text{x} = \dfrac{1}{7} \Rightarrow \text{x} = \dfrac{\dfrac{1}{7}}{4} \Rightarrow \text{x} = \dfrac{1}{7}\cdot \dfrac{1}{4} \Rightarrow \text{x} = \dfrac{1}{7\cdot 4} \Rightarrow \\ \\ \Rightarrow \boxed{\text{x} = \dfrac{1}{28}}$

Answer 2

a)x=21:7=3
b)x=3:9=1/3
c)5x=2/3
x=2/3 : 5=2/15
d)4x=1/7
x=1/7 : 4=1/28