I'll start 18 and 22 for you, and you should then be able to do the rest on your own!
For 18, what we literally do is apply the distance formula for all the points and add them up. For B to C, we get the distance between them to be
sqrt((x1-x2)^2+(y1-y2)^2)=sqrt((0-4)^2+(3-(-1))^2)=sqrt((-4)^2+4^2)=sqrt(16+16)=sqrt(32). Repeat the process for C to E, E and F, and F to B then add the results up to get your answer!
For 22, since the area of a rectangle is length*width (we know given the right angles and that the opposite sides are equal in how long they are), we can multiply 2 perpendicular lines, for example, BC and CE to get sqrt(32)*sqrt(8)=16 as the area
Divide 80/3 which equals 26.6. So it take Courtney 26.6 minutes to walk 1 mile. Then divide 110/26.6 which equals 4.1.
Courtney walls 4.1 miles in 110 minutes.
That variable from the number of black marble divide by all marble.
5/4+7+5 = 0.3125
You put 15 over 65 is equal to 50 over x, then you multiply diagonally so 15x = 3250 then you divide both sides by 15 to get 216.67 which means 50 pencils equals 2.17 dollars
increase in x results in the decrease in y
