-5x+8y=-21/3x-4y=15 systems of equations

News cameras take an overhead picture of a crowd at an outdoor event journalist then count the total number of people in the picture and use the sample of estimate the total number of people in the crowd this process is an example of

Data are collected to see how many ice-cream cones are sold at a ballpark in a week. day 1 is sunday and day 7 is the following saturday. use the data from the table to create a scatter plot.

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)