Robert graded his friend Sam's practice test and a him a 72% Sam checked it again in found that he really made a 80% Robert said relax i only made an error of 8%Is robert correct

Jackie purchased 3 bottles of water and 2 cups of coffee for a family for $7.35. brian bought 4 bottles of water and 1 cup of coffee for his family for $7.15. how much does each bottle of water cost? how much does each cup of coffee cost? i need this done

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?

Which is the focus of a parabola with equation y2=4x