Eric practiced piano and guitar for total of 8 hours this week. he practiced the piano for 1/4 of that time. how many hours did eric practice the piano this week?

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.