1) 1/3 -(+2/3) = 1/3 - 2/3 = (1-2)/3 = -1/3
2) -2/5 - (-3/5) = -2/5 + 3/5= (-2+3)/5 = 1/5
3) ⇔ 2)
4) -3/7 -(+4/7) = -37 - 4/7 = (-3 - 4)/7 = -1
5) 5/8 - (-7/8) = 5/8+7/8 = (5+7)/8 = 12/8 = 1'4/8 = 1'1/2 =1,5
6) -1/9 - (+2/9) = -1/9 -2/9 = -(1+2)/9 = - 3/9 = -1/3