Am i doing these right? be honest and if not mind explaining step by step how to? ty in advance

Amerchant has coffee worth $60 a pound that she wishes to mix with 50 pounds of coffee worth $90 a pound to get a mixture that she will sell for $70 a pound. how many pounds of the & 60 coffee should be used?

An air conditioning system can circulate 350 cubic feet of air per minute. how many cubic yards of air can it circulate per minute?

Which is the equation of a line perpendicular to the line with the equation 3x+4y=8