Question

Please don't give a long answer

Answer 1

Part A

2400 - 40x = 600

As she has not studied 600 flashcards still, we subtract unit rate from total.

Part B

40x - 600 = 2400

Here 'x' represent per hour. As he rents studio space for 600, subtracting this from total he earns by charging his students gives us the profit.

Part C

(600 + 40)x = 2400

Here 'x' represent mass. As masses are same for both. They can be joined.