Question

Find two numbers such that twice of the first added to the second gives $21$, and twice the second added to the first gives $27$.

• A. $5$ and $11$
• B. $9$ and $16$
• C. $3$ and $18$
• D. $3$ and $17$

Answer 1

The correct option is A $5$ and $11$

Let the first number is $x$ and second is $y$

Given twice of first added with second gives $21$

$\therefore 2x+y=21$ ...$\left(1\right)$

And given twice of second added with first gives $27$

$\therefore x+2y=27$ ...$\left(2\right)$

Multiply $\left(1\right)$ by $2$

Then $4x+2y=42$ ...$\left(3\right)$

Subtract $\left(3\right)$ with $\left(2\right)$

Then $3x=15$

Or $x=5$

Put the value of $x=5$ in $\left(1\right)$

Then $10+y=21$

Or $y=21-10$

Or $y=11$

Then first number is $5$ and second is $11$.