please can the following be solved without using calculators?

6 WPSOffice File Edit View Insert Format Tools Tables Workspace Window Help . ' Tue'l7Au96109pm . Home N his 'l' um in F-m'i r. u Guest EETE' : if 'i r\" \"W\" a ' _--B-=ccoa 4' . w F . ' ' ll m: in me A straight line passes through the point P (3, a) and Q (b,-19). The midpoint of line PO is (-2, 10). Find the equation of the line PO. (3 marks) Sol: y = 29X 48 Question :1: An electricity company supplies electricity for a month on the following plans: Plan A: a fixed supply charge of $20 plus 25 cents per unit of electricity used. Plan B: a fixed supply charge of $40 plus 15 cents per unit of electricity used. Let n be the number of units of electricity used in a month. Find expressions for CA, the monthly charge for Plan A, and for CE, the monthly charge for Plan B, in terms of n. Sketch the graphs of the charges for each plan against n on the same set of Find the number of units and the cost for which both plans cost the same amount. 3Ameooooaewe an aimkwnesammee_