You are buying decorations for a birthday party. six rolls of crepe paper and 20 balloons cost $11.90. after you start decorating, you need more supplies. you buy 2 more rolls of crepe paper and 15 more balloons for $6.05. how much did each roll of crepe paper cost?

Let's let

C = Creepers

B = Balloons

1) 6C + 20B = 11.9  

2) 2C + 15B = 6.05

Eliminate

16C + 20B = 11.9 x3  

-2C + 15B = 6.05 x4

18C + 60B = 35.7  

-8C + 60B = 24.2

10C/10 = 11.5/10  

C = 1.15

answerpeople organize large projects such as levee-building;

heat from the core of the earth causes convection currents to occur in the mantle. these currents slowly move the crust around.