4,. 2, 1, 3
900-(600-130•4):10=892
1).......2).........3).............4)900
130....600.....80|10......-......8
×..4...-520...........----......------
-----....------.....80|8........892
520......80...............................
2,. 3,. 1
800-250+140:5=578
1)..............2).........3)
140|5.......800....550
........----...-250...+.28
10...|28....------....-----
..40...........550....578
..40...........