What times what times with equals -80

What situation is an example of an observational study

Asmall business produces and sells balls. the fixed costs are $20 and each ball costs $4.32 to produce. each ball sells for $8.32. write the equations for the total cost, c, and the revenue, r, then use the graphing method to determine how many balls must be sold to break even.

Michael is training for a marathon. in his first week he plans to run 8miles. what path should he take