Sum of  

-5/21

and

7/9

in Simplest Form

Given:   +
Since the denominators are not common (not the same), we need to find the Least Common Denominator (LCD), which is equivalent to the Least Common Multiple of 9 and 21:
LCD = LCM(9, 21) = 63
Express the given fractions as equivalent fractions with respect to the LCD (63):
=   and   = As a result,   + = +
Since the equivalent fractions have common denominators, we can add the numerators:
+ = = is in Simplest Form since the Greatest Common Factor of 34 and 63 equals 1, GCF(34, 63) = 1Therefore, the Sum of  

-5/21

and

7/9

is equal to

34/63

in Simplest Form:  

-5/21

+

7/9

=

34/63

Note:   + = −