Which expression is equivalent to21^3 sqrt15 - 9^3 sqrt 15 ? A.12
B.30^3 sqrt 15
C.12^3 sqrt 5
D.12^3 sqrt 15
I have tried to complete this And I get stuck like 15 mins into it.

Just tell me how to set up the equation.

Ineed someone to me answer my question i have to have this done and knocked out

The first week samantha learned to read braille, she could read 10 words per minute. in the second week she increased her speed by 20%. in the third week she increased her speed again by another 25%. how many words could she read per minute by the third week? hurry and tell me!