(3/5 + -1/4)/(7/10)
get a common denominator of 20
3/5 * 4/4 =12/20
-1/4 * 5/5 = -5/20
7/10 *2/2 = 17/20
replace
(12/20 - 5/20)/(14/20)
add the top
(7/20)/(14/20)
copy dot flip
7/20 * 20/14
7/14
1/2
