35+23+Х=100. (30-15)+У=80. Х-(23+17)=60. а+(45-30)=75. 70-а=8+9+2. х+12=50-(15+5)

1. 35 + 23 + x = 100;

58 + x = 100;

x = 100 - 58;

x = 42;

Проверим:

35 + 23 + 42 = 100;

58 + 42 = 100;

100 = 100;

2. (30 - 15) + y = 80;

15 + y = 80;

y = 80 - 15;

y = 65;

Проверим:

(30 - 15) + 65 = 80;

15 + 65 = 80;

80 = 80;

3.  x - (23 + 17) = 60;

x - 40 = 60;

x = 60 + 40;

x = 100;

Проверим:

100 - (23 + 17) = 60;

100 - 40 = 60;

60 = 60;

4. а + (45 - 30) = 75;

a + 15 = 75;

a = 75 - 15;

a = 60;

Проверим:

60 + 15 = 75;

75 = 75;

5. 70 - а = 8 + 9 + 2;

-a = 19 - 70;

a = -19 + 70;

a = 51;

Проверим:

70 - 51 = 19;

19 = 19;

6. х + 12 = 50 - (15 + 5);

x = 50 - 20 - 12;

x = 30 - 12;

x = 18;

Проверим:

18 + 12 = 50 - (15 + 5);

30 = 50 - 20;

30 = 30.