Question

The sum of four times a number and 13 is 65. Find the number.

• A. 16
• B. 15
• C. 14
• D. 13

Answer 1

The correct option is D 13

Consider the number as x.
Four times the number = 4x
Sum of four times the number and $13=4x+13$
The sum of four times a number and 13 is 65.
$\therefore 4x+13=65$
Using trail and error method:
Substitute x = 16, we get $4x+13=4\left(16\right)+13=64+13=77,$ which is not equal to 65.
Substitute x = 15, we get $4x+13=4\left(15\right)+13=60+13=73,$ which is not equal to 65.
Substitute x = 14, we get $4x+13=4\left(14\right)+13=56+13=69,$ which is not equal to 65.
Substitute x = 13, we get $4x+13=4\left(13\right)+13=52+13=65,$ which is equal to 65.
$\therefore$ x = 13 is the correct answer.