If his best time is x, and the best time is smaller, then (1+1/3)*x=his second best time. If x+4=his second best time (since his second best time is 4 seconds slower), then (1+1/3)*x=x+4. Multiplying it out, we get (3/3+1/3)*x=x+4
=4x/3=x+4. Subtracting x from both sides, we get 4x/3-3x/3=x/3=4. Multiplying both sides by 3, we get x=12=his best time
C is your answer.
Without calculating anything else, you can look at the minimum and maximum values in your data set of 6 and 35. C is the only one that has those correct.
Just make sure that the numbers are in order before you analyze.
The area in degrees of a triangle is 180
So...
A+B+C=180
19+B+102=180
121+B=180
B=59°
