answer fast math ! a coffee company wants a new flavor of cajun coffee. how many pounds of coffee worth $ 7 a pound should be added to 30 pounds of coffee worth $ 3 a pound to get a mixture worth $ 5 a pound? to get a mixture worth $ 5 a pounds of coffee should be added.

5 lbs

Step-by-step explanation:

1)  x = lbs. of coffee at $7 per lb

2)  (7)(x) + (4)(10) = (5)(x + 10)

3) 7x + 40 = 5x + 50

   7x - 5x = 50 - 40

         2x = 10

           x = 5 (lbs. of coffee at $7 per lb.)

The answer to your problem is 5. Hope this helps

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12