Bonsoir!
a. 1/3 + 7/6 = 1*2/3*2 + 7/6 = 2/6 +7/6 = 9/6 = 3*3/3*2 = 3/2
b. 3/4 - 7/12 = 3*3/4*3 - 7/12 = 9/12 - 7/12 = 2/12 =2*1/6*2 = 1/6
c. 4/25 - 13/50 = 4*2/25*2 - 13/50 = 8/50 - 13/50 = -5/50 = -1*5/10*5 = -1/10
Voila! :D
