6/8+1/4=6/8+2/8=8/8=1
10/6-1/7=70/42-6/42=64/42=32/21
3/3-12/13=39/39-36/39=3/39=1/13
4/3-11/11=44/33-33/33=11/33=1/3
/ inseamna linia de fracție