please help and show working out

1. The midpoint of the line joining (k,2h) and (9k,6h+2) is (20,-11). Find k and h.

2. A factory produces 25 components at a cost of $830, and on another run produces 35 components at a cost of $1050. Find an expression relating the cost (C) to the number of components (n) produced, assuming a linear relationship.

3. ImageShack - Hosting :: mathxw9.jpg

I'm sorry it is upside down