Answer:
let the number be N
according to question, N + 20 = 2n - 5
= 20 + 5 = 2n - N
= 25 = N
let's check
N + 20 = 2n - 5
= 25 + 20 = (2 × 25) - 5
= 45 = 50 - 5
= 45 = 45 ✓