If a quadrilateral is inscribed in a circle, then its opposite angles are supplementary:
![85+C=180](https://img.qammunity.org/2023/formulas/mathematics/college/uxeabgt4ldb4feeai71ilb5ntv81ylpw43.png)
![C=180-85=95](https://img.qammunity.org/2023/formulas/mathematics/college/eu6cm8wl2nawd1rfgjhgrjfwpvgjomfr4c.png)
So, m∠C=95
Inscribed angles are half the measure of the arc they subtend. (The latter statement can be used to prove the former one.)
D = 144°/2 = 72°
F = 180° -D = 180° -72° = 108°
And CDE=95+72+85=252°