Need help 15 points to the right answer plus crown thing

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?

An angle that measures between 90 and 180° is called a(,

Just tell me how to set up the equation.