The answer is 7/20. 1/4= 5/20 and 3/5 = 12/20
What I did was find the GCF (greatest common factor) of both 4 and 5 which was 20. Then I multiplied both numerators by the same number I multiplied the denominator with. Afterwards I subtracted both numerators (12-5) and this equals to 7
Hope that helps