[tex] \frac{ab-ac}{z} =x [/tex]
So firstly, you want to multiply z on both sides[tex] ab-ac=xz [/tex]
Next, factor out a on the left side: [tex] a(b-c)=xz [/tex]
Lastly, divide by b-c on both sides, and your answer will be [tex] a=\frac{xz}{b-c} [/tex]
