This triangle has 60 degrees already. Remember that the sum of all triangles have to be 180.
Since we have two y's we can simplify it as 2y + 60 = 180.
We can now set this up as an algebraic equation.
2y + 60 = 180
Subtract 60 from both sides.
2y = 120
Divide both sides by 2
y = 60.
Y = 60, your answer is D.)
I hope this helps!
Answer: C
<u>Step-by-step explanation:</u>
∑ 8(
)⁽ⁿ⁻¹⁾ from n = 1 to n = 5
n = 1 → 8(
)⁽¹⁻¹⁾
= 8 = 
n = 2 → 8(
)⁽²⁻¹⁾
=
=
n = 3 → 8(
)⁽³⁻¹⁾
=
= 
n = 4 → 8(
)⁽⁴⁻¹⁾
=
= 
n = 5 → 8(
)⁽⁵⁻¹⁾
=
= 
Sum = 
= 408.99