Answer :

243 + 62 - 28 = n
n = 305 - 28
n = 277
9 × 27 + 2 × 31 - 28 = n
9 × 27 + 2 × 31 - 28 =
243 + 2 × 31 - 28 =
243 + 62 - 28 =
 305 - 28 =
277

n = 277