A: the mean salary is $500.
400+500+600=1500/3=500
b: the median is $500 also.
The pack of pencils weighs 21.6 grams because 0.9 times 24 is 21.6
At x=0 y=6 the y intercept. The rate is -0.25 so the equation is y=6-0.25x. The ordered pair is (x,6-0.25x).