1 foot is 12 inches
Convert everything to inches:
28 x 12 = 336 in.
39 x 12 = 468 in.
Add all the inches together:
336 + 468 + 7 + 8 = 819 in.
The answer is 819 inches.
Answer:
65 cm
Step-by-step explanation:
See the attached image. The Pythagorean Theorem says in a right triangle, (leg)^2 + (leg)^2 = (hypotenuse)^2.

51,000
5 in the ten thousands,
The thousands value is 1, the hundreds is 4 (less than 5 so we round down)
I'm assuming you're looking to find the expanded form of the number?
This number is in scientific notation. The easiest way to convert it to a normal number is to move the decimal place 14 to the right. I've attached a picture showing how to do this. You should get 630,000,000,000,000
There's a faster way to do this - notice that you need to move the decimal 14 to the right, and there's one number already after the decimal place. Therefore, 13 places will be filled with zeros. So, just write out 63 and add 13 zeros.
For more general help on scientific notation, check out these videos: https://www.khanacademy.org/math/pre-algebra/pre-algebra-exponents-radicals/pre-algebra-scientific-notation/v/scientific-notation-old
Hope that helps! Feel free to message me or leave a comment if I can clarify anything :)