(5 5/28 - (5 1/3)*1,25 - 1 16/21) : (-1,5) =
= (145/28 - 16/3*5/4 - 37/21) : (-3/2) =
= (145/28 - 20/3 -37/21) * (-2/3) =
= (145*3 - 20*4*7 - 37*4) / (3*4*7) * (-2/3) =
= (435 - 560 - 148) / 84 * (-2/3) = -273/84 * (-2/3) = (7*3*13)/(7*4*3)*(2/3) = 13/6