7)
60°
x + 83
40°
A) 7
C) -5
B) -11
D) -3

-3

Step-by-step explanation:

Using the Triangle Sum Theorem, we can prove that m<A + m<B + m<C = 180⁰. Looking at the triangle above, it has given us two measurements. We have to find the third measurement. In order to find the third measurement we will use the Triangle Sum Theorem.

m<A + m<B + m<C = 180⁰

x + 83 + 60⁰ + 40⁰ = 180⁰

x + 183⁰ = 180⁰

x + 183⁰ - 183⁰ = 180⁰ - 183⁰

x = -3

Now plug in -3 in the x place.

x + 83

-3 + 83 = 80⁰

Let us make sure that our Triangle Sum Theorem is right.

m<A + m<B + m<C = 180⁰

80⁰ + 60⁰ + 40⁰ = 180⁰

180⁰ = 180⁰

So this makes our answer true. Hope this helps, thank you :) !!