а) 28/5 * (-25/21) = -4 * 5/3 = -20/3 = -6 2/3
б) -20/9 * (-9/16) = 20/16 = 5/4 = 1,25
в) -763/650 = -1 113/650
г) -4242/0,07= -4242*100/7= -60600
д) 7.4 + 10.3 - 1.7 = 17.7 - 1.7 = 16
е) -0,027+0,3 = 0,273
