By what number should-15/56 be divided to get -5/6

pls pls pls pls I need your help ​

Write a corresponding real world problem to represent 2x - 125=400

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.

How do i do this activity, is appreciated