PLEASE HELP ME WITH THIS HARD QUESTION

Obs : The answer is 60°, but, i need to understand, if possible, why this is the value

Step-by-step explanation:

Well if I am right the triangle ACD is right triangle which means that up to D is 90° angle and when you know that you can see that smaller one can't be 60°

problem:

f(x) = - 2/3x + 5; f(5/2)

substitute 5/2 in for x:

f(5/2) = -2/3(5/2) + 5

simplify the right side:

f(5/2) = -5/3 + 5

f(5/2) = 10/3

f(5/2) = 10/3

i hope this !

answer: idk

step-by-step explanation: