The average = 1/2 (sum of the two bases) = 1/2 ( 16.8 + 6.9) = 11.85 yards
Presuming that I am reading the question correctly, the answer is D. A trigonometric table would provide all of the ratios of the sides in relationship to the angles. Sin, cos, and tan are just one example of the ratio.
60/2 equals 30 then 30x4 is 120. Is parents give him a 120$