Question

When ​one-fourth of a number is added to ​one-fifth of the​ number, the sum is 18. What is the​ number?

Answer 1

The number is 40.

Step-by-step explanation:

Let the number be n.

When ​one-fourth of a number is added to ​one-fifth of the​ number, the sum is 18

          $\frac{n}{4}+\frac{n}{5}=18\\\\\frac{5n+4n}{4\times 5}=18\\\\9n=4\times 5\times 18\\\\n=20\times 2\\\\n=40$

The number is 40.

Answer 2

Answer:

unknown number is 40

Step-by-step explanation:

 Let x be the unknown number

one-fourth of a number is added to ​one-fifth of the​ number

$\frac{1}{4}x+\frac{1}{5} x$

sum is 18

$\frac{1}{4}x+\frac{1}{5} x=18$

To solve for x take LCD 20

$\frac{5}{20}x+\frac{4}{20} x=18\\ \frac{9}{20} x=18$

multiply both sides by 20

$9x= 360$

divide both sides by 9

x=40