Henry is buying school supplies for the start of the school year. for every 3 pencils he buys 2 pens. if henry buys 21 pencils ,how many total pencils and pens dis henry purchase?

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.)