Проверкой если можно 1)2*x+4*x-3=15 2)7*x-x+1=19 3)21*a+4*а=100 4)c+с+12=44

1) 2х + 4х = 18
6х = 18
х = 3
2 × 3 + 4 × 3 - 3 =15
6 + 12 - 3 = 15.
15=15
2)7х - х = 18
6х = 18
х = 3
21 - 3 + 1 = 19
19 = 19.
3)25а = 100
а = 4
84 + 16 = 100
100 = 100
4)2с = 32
с = 16
16+16+12=44
44=44.

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