I tried to solve the following question and I'm doing something painfully wrong... what am I missing that it's this far off?

Question #4

(3^rd Degree Price Discrimination)

A Monopolist sells beer in two separate markets.They must decide how much to sell in each market in order to maximize their total profits.

The demand in the Canadian Market is :Q_Canada = 1120 - 10P_Canada

The demand in the United States Market is:Q_USA = 660 - 20P_USA

MC = MR

If Total Cost is:TC = 10 + 5(Q_USA +Q_Canada)

A.Calculate the Price and Quantity if the Monopolist Maximized their profit and sells in both markets?(8 Points)

a.Canada

i.Q_Canada = 1120 - 10P_Canada

1.10P = 1120-Qcanada

2.P=112 - 0.1Qcanada

ii.TR= (112-0.1Q)Q

1.TR=112Q-0.1Q²

2.MR=112-0.2Q

iii.Marginal cost = 5

1.112-.2Q=5

2.107=.2Q

3.535=Quantity for Canada

iv.P=112-0.1(535)=58.50 Price for Canada

b.USA

i.Q=660-20P

1.20P=660-Q

2.P=33-0.05Q

ii.TR=(22-0.05Q)Q

1.TR=22Q-0.05Q²

2.MR=22-0.1Q

iii.Marginal cost = 5

1.22-0.1Q=5

2.17=0.1Q

3.170=Quantity for USA

iv.P=33-0.05Q

1.33-0.05(170)=33-8.5=24.5 Price for USA

B.Calculate the Profit if he Monopolist Maximized their profit and sells in both markets?(6 Points)

a.TR=(Pusa*Qusa)+(Pcanada*Qcanada)

i.(170*24.5)+(535*58.50)

ii.4165+31297.50=35,462.50

b.TC= 10 + 5(170 +535)

i.10+850+2675=3,535

c.TR-TC=31,927.50 Profit

C.In the absence of 3^rd Degree Price Discrimination and the firm must sell at the same price in both markets, what is the price, quantity and total profit?(6 Points)

a.Qt=1120 - 10P+660 - 20P

i.Q=1780-30P

ii.30P=1780-Q

iii.P=59.33-0.03Q

b.TR=(59.33-0.03Q)Q

i.MR=59.33-0.06Q

c.MR=MC

i.59.33-0.06Q=5

ii.54.33=0.06Q

iii.905.5 is total Quantity -can't be right.