Answer
Pounds of trials =150
Pounds of cashews = 50
Step-by-step explanation
Let x be the number of pounds sold for trials and y be the number of pounds for cashews.
x + y = 200............................(i)
(9x + 13y)/(x+y) = 10
9x + 13y = 10(x+y)
9x + 13y = 10x + 10y
13y - 10y = 10x - 9x
x = 3y..................................(ii)
Substituting equation (ii) to equation (i).
x + y = 200
3y + y = 200
4y = 200
y= 50
x= 3(50)
x = 150