A boy earned $21.75 for babysitting. He spent of his earnings to buy lunch.
How much money does the boy spend on his lunch?

$21.75

Step-by-step explanation:

It says he spent his earnings on lunch.

Part A

The polynomial expression for the profit from selling and making 'y' cars is 0.003·y² - 10·y - 1,000,000

Part B

The profit made from selling 30,000 cars is 1,670,000

Step-by-step explanation:

Part A

Taking the revenue, 'R', made by the car company for the sale of 'y' cars as R = 0.003·y² + 10·y

The cost to produce 'y' cars, C = 20·y + 1,000,00

The profit, 'P', from making and selling 'y' cars is given as follows;

P = R - C

∴ 0.003·y² + 10·y - (20·y + 1,000,00) = 0.003·y² - 10·y - 1,000,00

An expression of the polynomial for the profit 'P', from selling and making 'y' cars is therefore presented as follows;

0.003·y² - 10·y - 1,000,000

Part B

The profit made from selling 30,000 cars, (y = 30,000) is given as follows;

= 0.003·y² - 10·y - 1,000,000

= 0.003 × 30,000,000² - 10×3,000 - 1,000,000 = 1,670,000

The profit made from selling 30,000 cars = 1,670,000.