The answer is 3.6 i know because i am a nerd
The expression that gives an angle that is coterminal with 300 is 300-720. Two angles are said to be coterminal if when they are drawn in a standard position, their terminal sides are on the same location. The expression gives an angle of 420 where when it is drawn the terminal sides are on the same location with the 300.
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Angles D and A are equal (from the statement bc the name of triangle starts with A and D)
Now set an equation of the angles so
45 = 5y -10
Add 10 on both sides
55 = 5y
divide by 5
y = 11