Solve :

10% of x + 20% of y = 24, 3x - y = 20

Given,

Equations : 10% of x + 20% of y = 24, 3x - y = 20

$\Rightarrow 10\% \text{ of } x + 20\% \text{ of } y = 24 \\[1em] \Rightarrow \dfrac{10}{100} \times x + \dfrac{20}{100} \times y = 24 \\[1em] \Rightarrow \dfrac{x}{10} + \dfrac{y}{5} = 24 \\[1em] \Rightarrow \dfrac{x + 2y}{10} = 24 \\[1em] \Rightarrow x + 2y = 240 \\[1em] \Rightarrow x = 240 - 2y ……..(1)$

Substituting value of x from equation (1) in 3x - y = 20, we get :

⇒ 3(240 - 2y) - y = 20

⇒ 720 - 6y - y = 20

⇒ 720 - 7y = 20

⇒ 7y = 720 - 20

⇒ 7y = 700

⇒ y = $\dfrac{700}{7}$ = 100.

Substituting value of y in equation (1), we get :

⇒ x = 240 - 2(100) = 240 - 200 = 40.

Hence, x = 40 and y = 100.