Question

Fill in the missing values to make the equations true.
log_4(7)+log_4(5)=log_4(?)
log_8(11)-log_8(?)=log_8(11/5)
2log_9(3)=log_9(?)

Answer 1

the main formulas of log are: 
log A + logB =log A*B
log A - logB =log A/B
log A ^p= p logA

so 
log_4(7)+log_4(5)=log_4(7*5)=log_4(35)
log_8(11)-log_8(5)=log_8(11/5)
2log_9(3)=log_9(3)²