1) 5/24 + 5/16 = 10/48 + 15/48 = 25/48
2) 1 2/3 - 3/5 = 1 10/15 - 9/15 = 1 1/15
3) 25/48 * 1 1/15 = 25/48 * 16/15 = 5/9
4) 5/9 * 1 4/5 = 5/9 * 9/5 = 1
1. с*5+2859=3454
с*5=3454-2859
с*5=595
с=595:5
с=119
2. 18512-а*3=17732
а*3=18512-17732
а*3=780
а=780:3
а=260
(24:8)•3=9/24
(24:12)•5=10/24
10+9=19/24
24-19=5/12 отремонтировали за третью неделю
;-)