Melissa sells 4 hats for a total of $68.64 before tax.

how many hats does melissa sell if the total is $154.44 before tax

a, 7

b. 8

c. 9

d. 10

For this case, the first thing we must do is find the unit cost.

We have then:

We now look for the number of hats that can be purchased with $ 154.44.

We have then:

Therefore, you can buy 9 hats with $ 154.44.

Melissa sells 9 hats.

C. 9

3. parallelogram

step-by-step explanation:

we turn each of our sides into direction vectors

ab=b-a=(3 - 7, 1 - 0) = (-4, 1)

bc=c-b=(1,6)

cd=d-c=(4,-1)

da=a-d=(-1,-6)

we see how the opposite sides have negated direction vectors; this is characteristic of a parallelogram.   we have congruent sides ab=cd and bc=da with unequal lengths because 1^2+6^2 is different from (-4)^2+1^2.   so it's not a square or a rhombus.  

we check the dot product of direction vectors of adjacent sides.   we have

ab dot bc = -4(1) + 1(6) = 2

that's not zero so the sides are not perpendicular.   we've ruled out rectangle.

the direction vectors indicate two pairs of congruent parallel sides, so we choose parallelogram over trapezoid.

correct

step-by-step explanation: