NEED HELP ASAP

A deli owner made a probability distribution chart for the meat choices of their customers’ sandwiches when the sandwiches contain only one meat.

Ham 0.28
Turkey 0.31
Roast Beef 0.19
Tuna ?
Salam i0.13

What is the missing probability in the table?

a0
b0.09
c0.20
d0.50