[tex] \frac{ab}{2} [/tex] = 2a - 1
2([tex] \frac{ab}{2} [/tex]) = 2(2a - 1) multiplied both sides by 2
ab = 4a - 2 distributed the 2 on the right side
ab - 4a = -2 subtracted 4a from both sides
a(b - 4) = -2 factored out "a" from the left side
a = [tex] \frac{-2}{b - 4} [/tex] divided (b - 4) on both sides
Answer: a = [tex] \frac{-2}{b - 4} [/tex]
