<span>а) 12х-11х+9=25
х+9=25
х=25-9
х=16
</span>
б) 293-18а=95
18а=293-95
18а=198
а=198:18
а=11- нужный ответ
в) 591:у-16=181
591:у=181+16
591:у=197
у=591:197
у=3
<span>г) 3в+в+24=48
4в+24=48
4в=48-24
4в=24
в=24:4
в=6
</span>
Вот тебе 1:50000 см. (легко)
3 - 2/5 * 3 1/3 = 3 - 2/5 * 10/3 = 3 - 2/1 * 2/3 = 3 - 4/3 = 9/3 - 4/3 = 5/3
- 3 : 5 1/4 - 2 1/2 : 7/8 = - 3 : 21/4 - 5/2 : 7/8 = - 3 * 4/21 - 5/2 * 8/7 =
= - 4/7 - 20/7 = - 24/7 = - 3 3/7
7/8 * 2 2/3 + (- 5/6) : 2 1/7 = 7/8 * 8/3 + (- 5/6) : 15/7 = 7/3 + (- 5/6) * 7/15 =
= 7/3 + (- 7/18) = 7/3 - 7/18 = 42/18 - 7/18 = 35/18
1/5 - ( 1 1/2 - 1 2/7 * 7/18) = 1/5 - (1 1/2 - 9/7 * 7/18) = 1/5 - (1 1/2 - 1/2) = 1/5 - 1 = 1/5 - 5/5 = - 4/5
6,3 - 7,2 - 2,5= -0,9 - 2,5 = -3,4