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.

$1.15

Step-by-step explanation:

The question is How much did each roll of crepe paper cost?

Let the cost of crepe paper be x

Let the cost of balloons be y.

Six rolls of crepe paper and 20 balloons cost $11.90. This will be:

6x + 20y = 11.90 i

2 more rolls of crepe paper and 15 more balloons for $6.05. This will be:

2x + 15y = 6.05 ii

6x + 20y = 11.90 i

2x + 15y = 6.05 ii

Multiply equation i by 15

Multiply equation ii by 20

90x + 300y = 178.50 iii

40x + 300y = 121 iv

Subtract iv from iii

50x = 57.50

x = 57.50/50

x = 1.15

Therefore, a crepe paper cost $1.15

answer: the answer is 35%