Find the value of a that makes a orthogonal, where a = matrix calculator

At the newest animated movie, for every 9 children, there are 4 adults. there are a total of 39 children and adults at the movie.

Simplify (2^5/3^2)^4 a. 2^20/3^8 b. 2^9/3^8 c. 8^5/12^2 d. 2/3^2

Fast! find the length of cu. the triangles are similar. show your work.