3 x 15 x 4 - 11 x 5 =
= 3 x 60 - 55
= 180 - 55
= 125
200 : 2 : 2 : 5 =
= 100 : 2 : 5
= 50 : 5
= 10
23 x 15 x 3 - 21 x 3 x 7 =
= 69 x 15 - 21 x 21
= 1035 - 441
= 594
