For large candles, the price is $10. They sold 42, we can say that. 42*10 is the total price or revenue without the cost to make the candles included. The cost to make the candles is $x. So we can say profit for large candles = (420 - 42x).
For small candles. The price is $5 and 56 are sold. The cost is again $x. So the profit for small candles is (280 - 56x).
So the total profit for part one of your question is (420 - 42x) + (280 - 56x).
In part to we are told that large candles cost $5 and small candles cost $3. Substituing this into are expression gives (420 - 42(5)) + (280 - 56(3)). This gives us $322. So the total profit is $322.
