(a)[2]
Simplify the expression $3u - 6w - 5u + 9w$.
(b)[4]
Emilio gets $m$ pencils at 40 cents apiece and 12 pens at 85 cents apiece. He hands over $\$20$ and is given $\$2.20$ change. Set up an equation in $m$ and solve it to determine how many pencils Emilio buys. Show your working.
(c)[2]
The variable $y$ varies directly with the cube of $(x - 2)$. When $y = 12$, $x = 4$. Find $y$ when $x = 5$.
(d)[3]
Write the expression as one fraction in simplest form: $\frac{3}{x-1} - \frac{4}{2x+1}$.