$\left(d^{-2}\cdot\:d^{-1}\right)^{\frac{4}{3}}$

$-2.5b=20.5$

$7 x - 4 = 3 x + 8$

$\frac{\sin\left(2x\right)}{\cos\left(2x\right)}$

$\left(x^2-3xy-y^2\right)+\left(9y^2-8xy+19x^2\right)$

$x^2+4x=-3$

$\frac{\frac{k^3-1^3}{k+1}}{\frac{k^2+kl+l^2}{\left(k+l\right)^2}}$