$-8y=-3y-15$

$\frac{\left(5^{-2}\cdot5^{-3}\right)^{-1}:5^2}{5^3\cdot\left(\left(5^2\right)^2\right)^{-1}}$

$\int\frac{x^5}{x^6-5}dx$

$91.71\cdot90.37$

$2\:cos\:x\::\:sen\:x=1$

$\frac{1}{4}-\frac{1}{4}\cos\left(2x\right)=\frac{1}{8}\sin\left(x\right)^2$

$2x^2-16x+33$