1. 38*4=154
2. 640:16=40
3. 900-152=748
4. 748+40=788
5. 788-100=688
Решение.........................
1)x+320=80*7
x+320=560
x=560-320
x=240
2)x-180=240/3
x-180=80
x=180+80
x=260
3)400-x=275+25
400-x=300
x=400-300
x=100
17 * (3х - 16) = 85
3х - 16 = 85 : 17
3х - 16 = 5
3х = 5 + 16
3х = 21
х = 21 : 3
х = 7
________________
17 * (3*7 - 16) = 85
17 * (21 - 16) = 85
17 * 5 = 85
85 = 85
Ответ: х = 7
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