Tan(angle) = opposite/adjacent
tan(x) = 90/51
x = arctan(90/51)
x = 60.461217740442
which rounds to 60 when rounding to the nearest whole number
Answer: 60
Absolute value is when you have either a positive or negative value within a set of "parentheses" or what look just like vertical lines and whatever is within those line stays or becomes positive. The only exception to this is when there is a negative on the outside to act upon the positive values within.
20 in. Because if you divide it by three then multiply it by four you get your answer.