$$-x-20=2x+1$$

$$\tan\left(x\right)\left(\sin\left(x\right)+\cos\left(x\right)\right)$$

$$10\sin^2x=5-5\cos2x$$

$$81d^2-19bd^4$$

$$\frac{1}{4}\left(sin\left(\frac{1}{8}\right)cos\left(\frac{1}{64}\right)+sin\left(\frac{3}{8}\right)cos\left(\frac{9}{64}\right)+sin\left(\frac{5}{8}\right)cos\left(\frac{25}{64}\right)+sin\left(\frac{7}{8}\right)cos\left(\frac{49}{64}\right)\right)$$

$$\frac{4x+1}{-2x-2}$$

$$-5\left(x-12\right)-15$$