x/4 + x/5 =18?

Basically, to add two fractions together, they need to have the same denominator. Multiply x/4 by 5/5, to get the bottom equal to 20, and multiply the x/5 by 4/4 to also get it to 20.

5x/20 + 4x/20 = 18 (common denominator)

9x/20 = 18 (add the fractions together)

9x = 360 (multiply both sides by 20 to get rid of the fraction)

x = 40 (divide both sides by 9 to solve for x)

5x + 4x = 360
9x = 360
x = 40

What's the numerator of the 2 fractions which total 18:
x/4 + x/5 = 18
5x + 4x = 360
9x = 360
x = 40

Answer: 40

Checking:
40/4 + 40/5 = 18
10 + 8 = 18

x/4 + x/5 = 18
5x + 4x = 20 * 18
9x = 360
x = 40

first you have to have a common denominators to sum two ratios: the common denomenator for these two ratios is: 20 so :
(5x+4x)/20=18
then multiply 20 by 18 and (5x+4x) by 1(denominator of 18)
5x+4x=360 then 9x=360 and the result is:
x=360/9=40

x/4 + x/5 = 18
5x + 4x = 20 * 18
9x = 360
x = 40

x/4 + x/5 = 18
20(x/4 + x/5) = 20(18)
5x + 4x = 360
9x = 360
x = 360/9
x = 40

First of all you have to make the denominator the same by finding the lowest common multiple of 4 and 5, that is 20.
so:

x/4 + x/5 =18
5x/20 + 4x/20 =18
9x/20 = 18

time both side by 20:

9x = 360 (then, divide both sides by 9)
x = 40

X= 40