Problem $1$

Perform the following mathematical operations with complex numbers, and express your answer in polar and rectangular form: $($show your work to receive full credits$)$

a$)\frac{42}{{?}_{45}}+\frac{62}{{?}_{60}}-\frac{70}{{?}_{120}}$

b$)\frac{(\frac{6}{{?}_{20}})(\frac{120}{{?}_{-}}40)(3+j8)}{\frac{2}{{?}_{30}}}$

c$)(\frac{0\mathrm{.}02}{{?}_{120}})(\frac{0\mathrm{.}6}{{?}_{35}})(\frac{40}{{?}_{-}}80)$

d$)\frac{(\frac{0\mathrm{.}4}{{?}_{-}}60)(\frac{300}{{?}_{-}}70)}{3-j9}$