\int_0^45 (60 - (X + 15))\, dX = \int_0^45 (45 - X)\, dX = \left[45X - \fracX^22\right]_0^45 = 45 \cdot 45 - \frac45^22 = 2025 - \frac20252 = \frac20252 - Portal da Acústica