
. 
2/3 + 3/4 = N (2*4)/(3*4) + (3*3)/(4*3) = N 8/12 + 9/12 = N 17/12 = N N = 17/12 = 1+5/12
3/4 + N = 4/5 N = 4/5 - 3/4 N = (4*4)/(5*4) - (3*5)/(4*5) N = 16/20 - 15/20 N = 1/20
N - 3/5 = 1/4 N = 1/4 + 3/5 N = (1*5)/(4*5) + (3*4)/(5*4) N = 5/20 + 12/20 N = 17/20
