1)(x-274)+356=481
(x-274)=481-356
(x-274)=125
x=125+274
x=399
2)478-(256+x)=143
(256+x)=478-143
(256+x)=335
x=335-256
x=79
3)659-(345-x)=427
(345-x)=659-427
(345-x)=232
x=345-232
x=113
4)791-(x-298)=683
(x-298)=791-683
(x-298)=108
x=108+298
x=406
1)(x-274)+356=481
(x-274)=481-356
(x-274)=125
x=125+274
x=399
2)478-(256+x)=143
(256+x)=478-143
(256+x)=335
x=335-256
x=79
3)659-(345-x)=427
(345-x)=659-427
(345-x)=232
x=345-232
x=113
4)791-(x-298)=683
(x-298)=791-683
(x-298)=108
x=108+298
x=406