CTET 2 Math and Science Jul 2019 Paper

A number is divisible by 72 if the given number is divisible by both 8 and 9.
Divisible by 8 : If last three digit is divisible by 8, then the given number is also divisible by 8.
Divisible by 9 : If the sum of digit is divisible by 9, then the given number is also divisible by 9.
Then, $\frac{58\mathit{y}}{8}\Rightarrow \mathit{y}=4$
$\because \frac{584}{8}=73$
$\frac{1+3+4+\mathit{x}+5+8+\mathit{y}}{9}$ $=\frac{21+\mathit{x}+\mathit{y}}{9}$ $=\frac{21+\mathit{x}+4}{9}$ $=\frac{25+\mathit{x}}{9}$
$\Rightarrow \mathit{x}=2$ $\because \frac{25+2}{9}=\frac{27}{9}=3$
∴ The value of x and y is 2, and 4 respectively
Then, 2x + y = 2 × 2 + 4 = 8.