I think its zero. i may be wrong
Answer:
B. 2x – 1 = 13 and x = 7
Step-by-step explanation:
We are given 4 equations and a solution for each. We have to tell which of the given solution satisfies the given equation.
Option A.
2x -1 = 13 and x = 6
Using this value in the equation, we get:
2(6) -1 = 13
12 - 1 = 13
11 = 13, which is not true. Hence this option is not valid
Option B.
2x - 1 = 13 and x = 7
Using the value in the equation, we get:
2(7) - 1 =13
14 - 1 =13
13 = 13, which is true. Hence this option is valid.
Option C.
2x + 1 =13 and x = 7
Using the value in the equation, we get:
2(7) + 1 = 13
15 = 13, which is not true. So this option is not valid
Option D.
2x - 1 = 13 and x = 11
Using this value in the equation, we get:
2(11) - 1 = 13
21 = 13, which is not true. Hence this option is not valid.
Answer:
Yellow = 18 spools of ribbon
Blue = 15 spools of ribbon
Bobby will have 3 more spools of yellow ribbon.

Hope I helped, also, I used the math thingy, which I haven't used before, so I'm not sure quite how this turned out, well, I guess we will see in a minute! But if it does not work I can try it just typing regularly.