1)
(k * 60) : 4 = 4.170
k * 60 = 4.170 * 4
k * 60 = 16.680
k = 16.680 : 60
k = 278
проверка:
(278 * 60) : 4 = 4.170
16.680 : 4 = 4.170
4.170 = 4.170
2)
(п + 4.906) : 9 = 480
n + 4.906 = 480 *9
п + 4.906 = 4.320
п = 4.320 - 4.906
п = - 586
проверка:
(-586 + 4.906) : 9 = 480
4.320 : 9 = 480
480 = 480
3)
28.360 : (u - 52.890) = 40
u - 52.890 = 28.360 : 40
u - 52.890 = 709
u = 709 + 52.890
u = 53.599
проверка:
28.360 : (53.599 - 52.890) = 40
28.360 : 709 = 40
40 = 40