Answer:

Step-by-step explanation:
Refer to the attached image.
A right triangle is considered so when one of its corners are 90°.
If sides a and b are equal in length, then the corners across from them are equal in size as well.
The only way for this to be possible is if both corners A and B(opposite of sides a and b) are 45°.
Pythagorean theorem
This theorem states that the square of a right triangle's long side is equal to the sum of the squares of the shorter sides.
In this case:

but since:

the equation can be solved by replacing a with b in the equation:

Answer:
They can buy 24 helmets.
Step-by-step explanation:
1 helmet = $15
$369 divided by $15 --> 24.6 --> 24 helmets
21:30 and 35: and 50 this is because 7 times 3 is 21, 10 times 3 is 30, and 7 times 5 is 35, and lastly 10 times 5 is 50
1. 5 and E, 6 and F, 7 and D, 8 and A, 9 and G