1)

x-250=4200

x=4200-250

x=3950

2)

x+x-250=4200

x+x=4200+250

x+x=4550

2x=4550

x= 4550÷2

x=2275

3)

x+250=4200

x=4200-250

x=3950

4)

x+x+250=4200

x+x=4200-250

x+x=3950

2x=3950

x= 3950÷2

x= 1975