Q59....b) as for profit max. firm MR=MC1=MC2
Q60....d) demand curve isn't there
Q61.....c)
Q62....consider three cases ie x1>x2, x2>x1 and x1=x2
U'll get x1+x2 ie option a)
I don't think the absence of the demand fx is a problem here. I guess we need to consider the firm to be a price-taker at P=3=MR, giving Q*=3 and profit = 4.5. Hence, 60 (a) and 61 (d).