Answer: g*5 + b*10 ≥ 50.
Explanation:
Let's define g = number of rings that land in green boxes.
and b = number of rings that land in blue boxes.
For each ring in the green box you earn 5 points, then if there are g rings in the green box, you have g*5 points.
And for the blue is similar, if there are b rings in the blue box, you will have b*10 points.
Then the total number of points that you will get is:
T = g*5 + b*10.
And the minimum that you need to win is 50 points, the inequality will be:
T ≥ 50
or
g*5 + b*10 ≥ 50.