b/-4+17=31

b/-4+17=31

There is no brackets here Brittany so the question should mean

(b/-4)+17=31

(b/-4)=31-17

b/-4=14

b=14*-4

b=-56

$${\frac{{\mathtt{b}}}{{\mathtt{13}}}} = {\mathtt{31}}$$

multiply 13 on both sides...

$${\mathtt{b}} = {\mathtt{13}}{\mathtt{\,\times\,}}{\mathtt{31}}$$

simplify....

b = 403