$$15m^2n+30mn$$

$$x^2+x<x+2$$

$$3^4\:x\:\:3^4\:x\:3^{-2}$$

$$\log\left(5x\right)=\log\left(5x-9\right)$$

$$\frac{dy}{dx}+3x^2+4y=0$$

$$20y=24y'$$

$$\frac{1+csc\left(x\right)}{cos\left(x\right)-cot\left(x\right)}$$