Jordan has gone into the nut business. He wants to make a mixture of walnuts and cashews that cost $1.00 per pound. How many pounds of walnuts that cost $0.80 per pound must be mixed with 8 pounds of cashews that costs $1.25 per pound to make his mixture of nuts cost $1.00 per pound?

Answers are
a.) 16 lbs.
b.) 11 lbs.
c.) 20 lbs.
d.) 10 lbs.

please explain your process in solving/your set up of the equation.