math
posted by soliman on .
Simplify and evaluate using distributive property of multiplcation
3x4(2x5)
I've tried many ways and can't come up with the same answer as the teacher. help please?

What answer does your teacher have?

3x8x+20

No. 3x8x+20=5x+20 or 5(4x)

ok..i guess that is where i'm confused
3x4(2x5)
3x(4X2x4X5)
3x(8x20) (this was my answer)
I still not sure how the teacher and you came up with +20 instead of 20? 
Two minuses make a plus.

3x(4X2x4X5)
The  outside the parentheses changes the sign of everything inside the parentheses. Therefore, the 4*3x becomes (8x) or 8x and the 4*5 becomes (20) or + 20. 
use the number line.is 458 closer to 450 or to 460

If you have a separate question to post, go to the top of the page and click on post a new question. Piggy backing onto another question rarely results in an answer for the piggy backer.

Than you all. Dr. Bob222 that was exactly what I was missing, I could not see where the 2 minuses where together since our teacher explained it differently. This was very clear.
Thank you.