Доброго времени суток ;)
Уровень : 1
24 - x = 15
13 + x = 37
x - 56 = 41
x - 391 = 9
152 + x = 257
392 - x = 22
517 - x = 420
Уровень : 2
(128 + 49) - x = 28
x - (133 + 75) = 32
(163 - x) - 117 = 0
145 - (x + 45) = 50
(39 + x) - 27 = 22
44 - (22 + x) = 22
78 - 16 - x = 41
Уровень : 3
(456 + 112) - x = 400
x - (203 + 303) = 34
(283 - x) - 33 = 0
382 - (x + 42) = 111
(536 + x) - 420 = 116
437 - (227 + x) = 0
468 - 217 - x = 51