Suppose the unit price of A is A, the unit price of B is B, and the sales quantity of A is C. According to the meaning of the question:

Ac *10%+BC * (1+40%) * 30% = (AC+1.4bc) * 20% solvable: a =1.4b.

So the total profit rate when the quantity is equal = AC *10%+BC * 30%/AC+BC =18.33%.

the second question