A candy store makes a 10-lb mixture of gummy worms, candy corn and sourballs. The cost of gummy worms is 1.00 per pound, candy corn cost 3.00 per pound, and sourballs cost 1.50 per pound. The mixture calls for three times as many gummy worms as candy corn. The total cost of the mixture is 15.00. How much of each ingredient did the store use?