The quadratic formula is:
and 
In this case, a = 2, b = -3, and c = -7
So, we can plug in the numbers to get:
and 
Simplifying, we get:
and 
You need to use a calculator to find what these would be in decimal form. The answer, rounded to the nearest tenth, is: x = 2.8, x = -1.3
2 m - polyester fabric: 4, cotton fabric: 14
6 m - polyester fabric: 12, cotton fabric: 42
8 m - polyester fabric: 16, cotton fabric: 56
9 m - polyester fabric: 18, cotton fabric: 63
check:
2 m: 4/14=2/7
6 m: 12/42=2/7
8 m: 16/56=2/7
9 m: 18/63 = 2/7
i think it would take about three minutes
The answer that i got for your question is the first answer.