There are 250 bricks used to build a wall that is 20 feet high how many bricks will be used to build a wall is 40 feet high?

500 bricks.

Step-by-step explanation:

There are 250 bricks used to build a wall that is 20 feet high how many bricks will be used to build a wall is 40 feet high?

To solve e the above question, we have:

20 feet high = 250 bricks

40 feet high = x bricks

Cross Multiply

20 feet × x bricks = 40 feet × 250 bricks

x bricks = 40 feet × 250 bricks/20 feet

x bricks = 500 bricks

Therefore, 500 bricks will be used to build a wall is 40 feet high.

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