I need help I'm in 5th grade

C. 3 5/18

Step-by-step explanation:

What we know:

Joel purchased 5 7/9 lb of grapes, while Jim purchased 2 1/2 lb.

What we need to find out:

How many more pounds of grapes does Joel have than Jim.

What we need to do:

Subtract 2 1/2 from 5 7/9.

But first, we need a common denominator.

2 and 9 don't have any common factors so multiply normally.

2 * 9 = 18

5 7/9 becomes 5 14/18, and 2 1/2 becomes 2 9/18.

Now to subtract.

(5 - 2) + ((14-9)/18)

3 + ((14-9)/18

3 + 5/18

Joel has 3 5/18 more pounds of grapes than Jim, so the answer is C.

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

i dony know

step-by-step explanation: