$\sin\left(x\right)^2\cdot\cos\left(x\right)^2+\cos\left(x\right)^2=\frac{1}{\sec\left(x\right)^2}$

$\frac{2x+4}{x+20}$

$4+-13+-1+-8$

$6+\frac{\left(-18\right)}{\left(-3\right)}\cdot2$

$\left(5a^2-2a\right)\left(21a^2b+5ab\right)$

$2\tan\left(x\right)=\frac{\sin\left(x\right)+\cos\left(x\right)\tan\left(x\right)}{\cos\left(w\right)}$

$7a+3a-4b+2b-c$