How do you solve this question?
A company has 3 products. They contribute to 30%, 30% and 40% of sales respectively.
They have profit margins of 15%, 30%, and 50% respectively.
If the client raises prices by 10% for Product A (assuming costs remain constant), what is the change in the company's total gross profit?
Is sales the same as total revenue (TR) or is it the same as profit ($\pi = TR - TC$)?
If it's the same as total revenue, I know that product A contributes 30% to the total sales, i.e.
$$ 0.3 \cdot TR = TR_A $$
Profit margin is given as $\tfrac{TR - TC}{TR}$, and if the profit margin of profit A is 10% then $$ \frac{1.1 \cdot TR - TC}{1.1 \cdot TR} = 1 - \frac{TC}{1.1 \cdot TR} $$
If the client raises prices by 10% for product A, the total revenue (TR) is now $$ TR' = 1.1 \cdot P \cdot Q = 1.1 \cdot TR $$
But how do i summarize? How can I conclude what the change in company's total gross profit is?