How do you solve this one problem?

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?

The solution set for 5v2 – 125 = 0 is

Ineeeeed this is due tomorrow and i dont know the answer can you find all the exponents