Use Pythagoras theorem

Two triangles are similar

(6+3)*12/2 - 6*8 /2 = 30
1, 3, 5, 7, 9 are the possible digits
meaning you have 5! possible combinations or 120 combinations
The longest side of a triangle must be less than the sum of the other 2 sides
2 senarios
the 3rd side is the longest
the 3rd side is not the longest
for the 3rd side is the longest
3rdside<28+42
3rdside<70
for 3rd side isn't the longest
42 is longest
42<28+3rdside
14<3rdside
so we've got
3rdside<70 and 14<3rdside
so
14<3rdside<70
the 3rd side can be any number from 14in to 70in except 14in and 70in
Step 1.
Calculate measure of angle α:

Step 2.
Calculate what fraction of the angle 360° is the angle α:

Step 3.
Calculate the circumference of the Earth (circle):

Step 4.
The length of arc is equal 1/40 of the circumference:


<h3>Answer: A) 628 miles</h3>
To answer this question we can propose the following equation:

Where:
x is the number of weeks elapsed.
d is the debt depending on the weeks.
Robert promised to pay at least $ 67 each week.
Therefore, after 5 weeks the debt of rober should be:


Then scenario A) is possible because
.
After 6 weeks:


Then scenario B) is possible because
.
After 7 weeks


Then scenario C) is possible because
.
After 8 weeks


So scenario D) is NOT possible because 
Finally the correct answer is option D.