Sravni uravnenia i reshi i ih: x: 20=360,x*20=360,30*x=210,30+x=210,8120-x=40,8120: x=40.

1. х*20=360
х=360÷20
х=18

2. 30*х=210
х=210÷30
х=7

3. 30+х=210
х=210-30
х=180

4. 8120-х=40
х=8120-40
х=8080

5. 8120÷х=40
х=8120÷40
х=203