1) 27+13=40
40-3=37
2) 27-3=24
24+13=37
3)13-3=10
27+10=37
a)
3x + 3 + 7x - 21 = 8x + 16
3x + 7x - 8x = 16 - 3 + 21
2x = 34
x = 17
б)
12x + 18 - 8x = 4x + 18
12x - 8x - 4x = 18 - 18
0 = 0
110х=9900
х=90
у*78=19734
78у=19734
у=253
1800=45z
45z=1800
z=40