How do you figured the way to divide 70 by 632

Math i have no idea how to do a and b

Determine the required value of the missing probability to make the distribution a discrete probability distribution. x p(x) 3 0.23 4 ? 5 0.51 6 0.08 p(4) = nothing  (type an integer or a decimal.)

On ryan's last social studies test there were two types of questions true/false worth 3 points each and multiple choice questions worth 4 points each