Answer :
1. Let x be the unknown number.
2. Translate the problem into an equation:
3(x + 11) = 45
3. Solve the equation:
3x + 33 = 45
3x = 45 - 33
3x = 12
x = 12 ÷ 3
x = 4
Therefore, the number is 4.
To check:
4 + 11 = 15
15 × 3 = 45
The number is 4.
