( -5/8) х (-4/5) х (-3/4) х (-2/3) х (-1/2)= -1/8
1) (-5/8) х (-4/5) = 1/2
2) 1/2 х (-3/4) = -3/8
3) (-3/8) х (-2/3) = 1/4
4) 1/4 х (-1/2) = -1/8
(-7/12) х (-6/7) х (-5/6) х (-4/5) + 2/3= 1
1) (-7/12) х (-6/7) = 1/2
2) 1/2 х (-5/6) = -5/12
3) (-5/12) х (-4/5) = 1/3
4) 1/3 + 2/3 = 1
(-11/15) х (-10/11) х (-9/10) + (-7/9) х (-6/7) + 4/15 = 1/3
1) (-11/15) х (-10/11) = 2/3
2) 2/3 х (-9/10) = -3/5
3) (-7/9) х (-6/7) =2/3
4) (-3/5) + 2/3 = 1/15
5) 1/15 +4/15 = 5/15 = 1/3