Question

2 questions in one.
Help?..

Answer 1

2. 3

3. 4^45

Explanation:

`{ ({5}^(4) ) }^(m) = {5}^(12) \\ = > {5}^(4m) = {5}^(12) \\ = > 4m = 12 \\ = > m = (12)/(4) \\ = > m = 3 \\ \\ number \: of \: books \: at \: library \\ = {({4}^(9))}^(5) * {4}^(0) \\ = {4}^(45) * 1 \\ = {4}^(45)`