1)
х - 270 = 302 + 48
х - 270 = 350
х = 350 + 270
х = 620
_______________
620 - 270 = 302 + 48
350 = 350
Ответ: х = 620
2)
820 - 310 + R = 900
510 + R = 900
R = 900 - 510
R = 390
__________________
820 - 310 + R = 900
510 + 390 = 900
900 = 900
Ответ: R = 390
Darknight (Sunny Storm)