Please I need help with step by step instructions

Complete the following Questions: Example 1.1.14 A frozen yogurt stand makes a profit of P(x) = 0.10x - 40 dollars when selling x scoops of yogurt per day. (a) Find the break-even sales level that is, the level at which P(x) = 0 (b) What sales level generates a daily profit of $30? (c) How many more scoops of yogurt will have to be sold to raise the daily profit from $30 to $40