How do you know the Arithmetic sequence

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?

In which direction does the left side of the graph of this function point? a(x) = 3x - x2 + 4x - 2

What is the absolute value of -100000000000000?