adding fractions with different denominators requires finding a common denominator
e.g.

an easy way to find a common denominator is to simplify multiply the denominators together
in this case it'd be 14
next, in order to add the fractions, we need to make both of them have denominator 14
for
, we multiply it by
. note that this is essentially multiplying it by 1, but we don't simplify now, we do it later

we have to multiply 5/7 by 2/2

now we can add the numerators

also, you can use a formula derived from using common denominators
