X=xmcos(wt+phi) and x=xmsin(wt+phi) are solution of equation (a+w^2x=0)

Abox contains 1 plain pencil and 4 pens. a second box contains 5 color pencils and 5 crayons. one item from each box is chosen at random. what is the probability that a plain pencil from the first box and a color pencil from the second box are selected? write your answer as a fraction in simplest form.

Can someone me and do the problem plz so i can understand it more better

Given a: b and b: c, find a: b: c. write the ratio in simplest form. a: b=6: 10 and b: c=21: 33