6 - 3a=21 whats the answer to that i have a hard time thinking about it.

Find the length of the following tangent segments to the circles centered at o and o' whose radii are 5 and 3 respectively and the distance between o and o' is 12. what is the tangent segment of cd?

Which shows the pre image of triangle xyz

The number of fish in a lake can be modeled by the exponential regression equation y=14.08 x 2.08^x where x represents the year