This is a sine law problem. I would check to see if it is going to work. Draw a perpendicular from the unmarked third angle to the base of the triangle. You are finding the height of the triangle. 2.8 must be greater than this height or the triangle has no solution.
Sin(20) = h/5.1 Multiply both sides by 5.1
5.1 * sin(20) = h
5.1 * 0.3420 = h
h = 1.744
Conclusion
Since 2.8 > 1.744 we do have a triangle [It was possible that we did not]7
Equation
Sin(x) / 5.1 = sin(20) / 2.8 Multiply both sides by 5.1
The shoes and purse each take up 1/4th of the circle (since 25 is 1/4th of 100) so we can eliminate the top 2 choices. Since the dress costs more than the bracelet it will take up more room leaving us with the bottom right circle as the answer.