How many pounds of walnuts that cost $7.60 per pound must be mixed with 6 pounds of cashews that costs $12 per pound to make a mixture of nuts that costs $9.25 per pound?
Select one:
a. 8 pounds
b. 10.5 pounds
c. 10 pounds
d. 12 pounds

Question

How many pounds of walnuts that cost $7.60 per pound must be mixed with 6 pounds of cashews that costs $12 per pound to make a mixture of nuts that costs $9.25 per pound?
Select one:
a. 8 pounds
 b. 10.5 pounds
 c. 10 pounds
 d. 12 pounds

aum · Answer

Cost of "x" ponds of walnuts = $7.60x
Cost of 6 pounds of cashews = $12 * 6 = $72

Total weight = (x+6) pounds
Total cost = $(7.60x + 72)

Cost per pound of the mixture = $(7.60x + 72) / (x + 6) = $9.25

Solve for x.

anonymous · Answer

but how do you find x thats what i dont get

aum · Answer

(7.60x + 72) / (x + 6) = 9.25
multiply both sides by (x+6)
7.6x + 72 = 9.25(x+6) 
7.6x + 72 = 9.25x + 55.5
isolate x.  First subtract 7.6x
72 = 1.65x + 55.5
subtract 55.5
16.5 = 1.65x
divide by 1.65
10 = x   or x = 10 pounds.

anonymous · Answer

do you divid by 1.65 both sides nd thx

aum · Answer

Yes. All operations should be done on both sides of the equation to keep the equation still valid.

anonymous · Answer

oh ok thnxs

aum · Answer

subtract 55.5  (done on both sides of the equation)
divide by 1.65  (done on both sides of the equation)

aum · Answer

yw.