Question 79928
(pounds of peanuts)(price per pound of peanuts) + (pounds of cashews)(price per pound of cashews) = (total pounds)(price per pound)

Everything is given except the the pounds of cashews, so we also don't know the total pounds.

If you let the pounds of cashews be x, then the total pounds will be x + 30. 

30(1.50) + x(5.00) = (30 + x)(3.00)

45 + 5x = 3x + 90

2x = 45

x = 22.5

There must be 22.5 pounds of cashews mixed with the 30 pounds of peanuts.