$14+9-5+6+9-100$

$\frac{dx}{dt}=-2-x$

$\left(\frac{2}{3}x-\frac{3}{2}\right)\left(\frac{2}{3}x+\frac{3}{2}\right)$

$55+24$

$4\frac{d^2y}{dx^2}-12\frac{dy}{dx}=-9$

$12\left(2\left(6x^4y-x^3yz^2\right)-5x^2y^3\right)$

$\left(2.5x^2-3.2y^2\right)-\left(3.5x^2-2.8y^2\right)$