Найдите корни уравнений

1. (x-16) * 5=420

2. (16+x) * 20=680

3. (200-x) * 6=1140

4. (x+30) * 110=7700

1. (x-16) * 5=420

5x - 80 = 420

5x = 420 + 80

5x = 500

x = 500 : 5

x = 100

2. (16+x) * 20=680

320 + 20x = 680

20 x = 680 - 320

20 x = 360

x = 360 : 20

x = 18

3. (200-x) * 6=1140

1200 - 6x = 1140

-6x = 1140 - 1200

-6x = - 60

x = 10

4. (x+30) * 110=7700

110x + 3300 = 7700

110x = 7700-3300

110x = 4400

x = 40