15-17 with explanations. Please!

my mistake for number 17. please do 15-16.

15. Toby's Tiny Toys have an expense equation of E = 12.45q +53,900. Toby's sell their toys for $16.50 a piece, and their revenue equation is R = 16.59. How many tiny toys do they have to sell to reach their breakeven point? 16. AAA Dance Shoes makes dancing shoes with leather soles. The shoes cost $29 to manufacturer. The fixed cost for the product line is $45,000. The company has determined their demand function to be q = -200p+ 30,000, where p is the price for each pair of shoes. Write the expense and revenue functions in terms of price. 17. Nancy works at a health club. She notices that the clients that run on the track for a longer period of time go a longer distance. If this is a causal relationship, explain the explanatory and response variable