4) (1 9/16 • 3 1/5 + 6 2/3 - 9 : 2 2/5) : (17 7/12 - 6 1/3) = (25/16 • 16/5 + 20/3 - 9 : 12/5) : (211/12 - 19/3) = (5 + 20/3 - 9 • 5/12) :45/4 = (5 + 20/3 - 9 • 5/12) • 4/45 = 95/12 • 4/45 = 19/3 • 1/9 = 19/27
5) (5,07 : 1/20 - 23,4 : 13/50) • 1/4 +0,074 • 1/2 = (507/100 • 20 - 117/5 • 50/13) • 1/4 + 37/500 • 1/2 = (507/5 - 90) • 1/4 + 37/1000 = 57/5 • 1/4 + 37/1000 = 2887/1000 = 2,887
6) (-31,5 : 63,4 -23,4 : (-11,7)) • (-2,4) = -0,5 - 117/5 : (- 117/10) • (- 12/5) = - 1/2 - 117/5 • 10/117 • 12/5 = - 1/2 - 2 • 12/5 = - 1/2 - 24/5 = - 53/10 = -5,3