How do you subtract #\frac { 2} { 3} - \frac { 1} { 5}#?

1 Answer
Mar 9, 2018

#7/15#

Explanation:

When adding or subtracting fractions, you must find a common denominator for both. Adding or subtracting straight across breaks math rules.

So we need to find a number that both #3# and #5# go into. The fastest way is to just multiply the two together.

#5*3=15#

Our common denominator is #15# (meaning both fractions now have a bottom of #15#). However, that is not all we do to give us the ability to subtract. When we multiplied each denominator to get #15#, we need to multiply the numerator on each fraction by the corresponding number:

#2/3 => (2(5))/(3(5)) => 10/15#

#1/5 => (1(3))/(5(3)) => 3/15#

Now that our fractions have common denominators, we can subtract. The numerators are the only ones to change.

#10/15-3/15#

#7/15#