6. Suppose you bought supplies for a party. Three rolls of streamers and 15 balloons cost $30. Later, you bought 2 rolls of streamers and 4 balloons for $11. How much did
each roll of streamers cost? How much did each balloon cost?

Streamers are $2.50 each

Balloons are $1.50 each

Step-by-step explanation:

Make a system of equations

3s + 15b = 30

2s + 4b = 11

Solve by elimination: multiply the top equation by 2 and the bottom equation by -3.

6s + 30b = 60

-6s -12b = -33

18b = 27

b = 1.5

Plug in 1.5 as b to find s

3s + 15(1.5) = 30

3s +22.5 = 30

3s = 7.5

s = 2.5

The streamers are $2.50 and the balloons are $1.50

step-by-step explanation: h: (- 3, 6)

m: (1, - 2)

o: (7, 6)

r: (- 9, - 2)

midpoint of hm: (- 1, 2)

midpoint of or: (- 1, 2)

therefore, b is the midpoint of both diagonals bisect each other !

to prove the diagonals are perpendicular, show that the product of the slopes = - 1