A) 13 students
b) 13 students
c) 37 students
3x-y=6, in order to be able to graph this you would have to change the equation to y=, so you need to subtract 3x from that side making it -y=-3x+6, now you need to y positive, so divide both sides by -1, thus making the equation look like y=3x-6, now if you can't plug this into a calculator to see what it would look like then you need to know what y=mx+b means. y is the equation you want to graph obviously, m = the slope, so our slope in this case would be -3, and b = our y intercept, so it would be (0,-6), so plot (0,-6) and use the slope to plot the rest of the points, some other points in this line should include (2,0), (-1,-9) and (4,6), just to name a few. Hope this helps.
18. 17.9
19. 21.1
20. I cant see the numbers sorry; if the sides are 6, √85 than it should have an angle of 40.6
Honestly just use desmos or mathyway
B) c - 1/5c - 40 = 120
c- (original cost) - 1/5c (sale) - 40(coupon)= 120(final cost)
Hope that helps! :)