5. Mr. Key and his wife order take-out food from a restaurant. The food
total of the bill was $67.70 and that is with tax already included. If they
added a 20% tip to the total, how much money did they spend?
O
$54.16
O $67.90
O
$81.24
O
$87.70

67.90

Step-by-step explanation:

67.70

20%

20. move the decimal to the left twice

.20 then add

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.