Answer: B. 60
Concept:
Here, we need to know the idea of the triangle angle sum theorem.
The triangle angle sum theorem states that the sum of interior angles is 180 degrees.
Explanation:
Given information
∠A = 90°
∠B = 30°
∠C = unknown
Given expression deducted from the triangle angle sum theorem
∠A + ∠B + ∠C = 180
Substitute values into the expression
90 + 30 + ∠C = 180
Combine like terms
120 + ∠C = 180
Subtract 120 on both sides
120 + ∠C - 120 = 180 - 120
∠C =
![\boxed{60}](https://img.qammunity.org/2022/formulas/mathematics/high-school/z5yh8tbw8u3bmlzh000bbczke3481hy4z9.png)
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