`x+ 227 = 105 + 201`
`x+ 227 = 306`
`x=306-227`
`x=79`
_______________________
`503 + x = 798`
`x=798 - 503`
`x=295`
________________
`x-483 =209`
`x=209+483`
`x=692`
___________________
`507 - x = 312`
`x=507-312`
`x=195`
_____________
`578 + ( x - 13 ) = 692`
`x-13=692 - 578`
`x-13=114`
`x=114+13`
`x=127`
___________________
`493 - ( x + 87 ) = 126`
`x + 87 = 493 -126`
`x+87=367`
`x=367-87`
`x=280`
a. x=79
b. x=295
c. x=692
d. x=195
e. x=127
f. x=280
OK nha bạn.