(Writing systems of Equations) Jenny bought supplies for a party. Three rolls of streamers and fifteen party hats costs $30.Later she bought two rolls of streamers and four party hats for 11$.Write a system of equations that can be used to determine the cost of each item.

A) 3S + 15H = 30.00

B) 2S + 4H = 11.00

We'll multiply B) by -1.5

B) -3S + -6H = -16.50  then we add this to A)

A) 3S + 15H = 30.00

9H = 13.50

1 Hat costs $1.50

That means 15 Hats cost 22.50 so equation A becomes:

3S + 22.50 = 30

3S = 7.50

1 Streamer costs $2.50

Step-by-step explanation:

3x^3-x^2+6x-9