Answer
$4(\cos 35^{\circ}+i\sin35^{\circ})$
Work Step by Step
Recall: If $z_{1}=r_{1}(\cos\theta_{1}+i\sin\theta_{1})$ and $z_{2}=r_{2}(\cos\theta_{2}+i\sin\theta_{2})$, then
$\frac{z_{1}}{z_{2}}=\frac{r_{1}}{r_{2}}[\cos(\theta_{1}-\theta_{2})+i\sin(\theta_{1}-\theta_{2})]$
Dividing according to the formula, we get
$\frac{20(\cos 75^{\circ}+i\sin 75^{\circ})}{5(\cos 40^{\circ}+i\sin40^{\circ})}=\frac{20}{5}[\cos (75^{\circ}-40^{\circ})+i\sin(75^{\circ}-40^{\circ})]$
$=4(\cos 35^{\circ}+i\sin35^{\circ})$
