5 girls to 2 boys, it’s not asking for boys and girls
If you want to cheat, paste the formula in Wolfram Alpha. However, this one is not that difficult. From the fact that x and y are squared you can infer that this is a circle. The 9 reveals that the radius r^2 is 9, so radius is 3.
The (x-2) tells us that the circle is shifted to the right by 2. Likewise, y+1 shifts it down by one. So the center is at (2,-1). If the equation would be x^2 + y^2 = 9, you'd have a circle exactly on the origin.
Hopefully this helps you break down the equation and pick the right picture!
To show that they used the same amount of ribbon you could take the 1 yard and divided into different sized equal groups.
1 yard divided by four equals 1/4 yard for each of four ribbons.
1 yard divided by six equals 1/6 yard for each of six ribbons.
You could have ribbons the size of 1/4 our yard and 1/6 yard, but you would have different amounts of each.
200/5 = 40 miles per inch. 40x7=280 actual miles.