a/5+15=-3 1/2

No prob, radio.....I gave you points for a "good effort"......it's always easy to make mistakes on here !!!!

$${\frac{{\mathtt{a}}}{{\mathtt{5}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{15}} = {\mathtt{\,-\,}}{\mathtt{3}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{1}}}{{\mathtt{2}}}}$$

$${\frac{{\mathtt{a}}}{{\mathtt{5}}}} = {\mathtt{\,-\,}}{\mathtt{3}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{1}}}{{\mathtt{2}}}}{\mathtt{\,-\,}}{\mathtt{15}}$$

$${\mathtt{a}} = {\mathtt{5}}{\mathtt{\,\times\,}}\left({\mathtt{\,-\,}}{\mathtt{3}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{1}}}{{\mathtt{2}}}}{\mathtt{\,-\,}}{\mathtt{15}}\right)$$

$${\mathtt{a}} = {\mathtt{5}}{\mathtt{\,\times\,}}\left({\mathtt{\,-\,}}{\mathtt{3}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{1}}}{{\mathtt{2}}}}{\mathtt{\,-\,}}{\mathtt{15}}\right) \Rightarrow {\mathtt{a}} = -{\mathtt{87.5}}$$

Or if on the right side was-(3+1/2)

$${\frac{{\mathtt{a}}}{{\mathtt{5}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{15}} = {\mathtt{\,-\,}}\left({\mathtt{3}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{1}}}{{\mathtt{2}}}}\right)$$

$${\mathtt{a}} = {\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{\,-\,}}\left({\mathtt{3}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{1}}}{{\mathtt{2}}}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{15}}$$

$${\mathtt{a}} = {\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{\,-\,}}\left({\mathtt{3}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{1}}}{{\mathtt{2}}}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{15}} \Rightarrow {\mathtt{a}} = -{\mathtt{2.5}}$$

I think we have.......

a/5 + 15 = -(3 + 1/2)      change -(3 + 1/2)  to -3.5 

a/5 + 15 = -3.5               subtract 15 from both sides

a/5 = -15 -3.5                 simplify

a/5 = -18.5                     multiply both sides by 5

a =   (-18.5) *(5)      =    -92.5

Ahh. Forgot to combine on each step.