Ricky's heartbeat is 70 beat per minute. How many days have elapsed if his heart beat a total of 504,000?

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?

What can you determine about the solutions of this system

Ineed in figuring out this problem.