We have the similar triangles. Therefore the lengths of the sides are in proportion:

Try multiplying each side of the equation by 3, and then
watch out when the answer jumps off the paper at you.
Check out the attached image for the answers.
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Statement 2 is blank, but it has the reasoning "Corresponding angles postulate"
Because BD || AE, we know that the corresponding angles are congruent.
One pair of corresponding angles is angle 1 and angle 4. This is because they are on the same side of the transversal AC and they are both above their parallel line counter-part. Similarly, angle 2 and angle 3 are another corresponding pair.
So you'll have "angle1=angle4, angle3=angle2" in the first blank slot
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Reason 3 is blank. The statement is that triangle ACE is similar to triangle BCD. The reason why the are similar is the AA (angle angle) similarity postulate. This says that if you know two pairs of angles are congruent, then the triangles are similar. The two pairs of angles were mentioned back on the previous line (line 2)
So you'll put "Angle-Angle Similarity Postulate" in the second blank.
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Look at the line just above the last line. Here we have
1 + (BA/CB) = 1 + (DE/CD)
If we subtract 1 from both sides, we end up with,
BA/CB = DE/CD
which is what will go in the last blank space
Side Note: The last statement will always be what you want to prove. So you can just look at the very top of the problem where it says "Prove:" under the "Given" part. Then just copy/paste the statement you want to prove, which in this case is BA/CB = DE/CD
Answer: The answer is:
d=220, b=300
Step-by-step explanation:
You could solve this problem using a series of equations:
d+b=520
b-80=d
How I solve this is:
If d+b=520, you could divide 520 by 2 and say that d and b's average is 260 (though that is not their value).
Then , you know that the difference between them is 80. Since the average is 260, you could add half of 80 (which is 40) and subtract the same to get 220 and 300, which, as you can see, have a difference of 80 and add up to 520. Now you have to find out which is which.
Since 80 fewer tickets were purchased at the door than before the concert (d+80=b (the second equation)), you know that the number of tickets at the door is the lesser number, making the answer:
d=220, b=300
Rocco would have to run diagonally 27 times