7. Wanda's Widgets used market surveys and linear regression to develop a demand function based on the wholesale price. The demand function is q = -140p + 9,000. The expense function is E = 2.00q + 16,000.
a. Express the expense function in terms of p.
b. At a price of $10.00, how many widgets are demanded?
c. How much does it cost to produce the number of widgets from part b?

I am so confused on how to answer these 3 sections, so if anyone could help I would really appreciate it!! ​