How do you solve this question and explanation -8=c/-10

Two blends of tea are mixed to make a blend that will be sold at the fair. black tea sells for $2.20 per pound and orange pekoe tea sells for $3.00 per pound. how much of each should be used to obtain a 4lb blend selling for $2.50 per pound?

You can find the constant of proportionality by finding the ratio of

The volume of a cube-shaped shipping container is 13,824 cubic inches. find the edge length of the shipping container.