solve the system of equations using a matrix with calculator

a. Astronomers have determined the number of stars in a small region of the universe to be 2,880,968 classified as red dwarfs, yellow, and blue stars. for every blue star there are 120 red dwarfs for every re dwarf there are 3000 yellow stars. determine the number of stars of each type in that region of the universe

b. Orange juice producers use three varieties of of oranges: Hamlin, Valencia, and navel. They want to make a juice mixture to sell at $3.00 a gallon. the Prices per gallon of these varieties of juice re $2.50, $3.50, and $2.80, respectively. To maintain their quality standards they use the same amount of Valencia and navel oranges. Determine the quantity of each juice used to produce 1 gallon of mixture.