What are 2 numbers equivalent for 8 3/4

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

Logan wants to know how many skateboards have defective parts. he inspects 20,000 skateboards and keeps track of the number of defects per board. use his probability distribution table to find the expected value for defects on a skateboard.

If you could answer these your a life saver