Question

What’s 13/18- 5/8??????

Answer 1

When adding or subtracting fractions that have a common denominator, simply subtract the numerators (top numbers) by each other. However, to subtract fractions with unlike denominators, find the LCD or "least common denominator". That is the lowest number both denominators can equate to.

$\frac{13}{18} - \frac{5}{8} [tex] (\frac{13}{18})( \frac{4}{1} ) - (\frac{5}{8})( \frac{9}{1})$[/tex]
The LCD of 8 and 18 is 72.
Some of the multiples of 8 are: 8, 16, 24, 32, 64, 72, 80, 88, 96, 104...

The multiples of 18 are: 18, 36, 54, 72, 90
The lowest common multiple is 72.

Multiply each fraction by what it takes for the denominator to equal 72.
8 multiplied by what number = 72
8*9=72
18 multiplied by what = 72
18*4=72
Multiply both fractions respectively 
13/18*4= 13*4/72
5/8*9 = 5*9/72
52/72 - 45/72
Simplify
52-45/72
7/72
This being the answer for the original expression

I hope this helps! If you have any question feel free to ask!