The measure of
is 50 degrees. The answer is D. 50°.
In triangle ABC, the sum of all interior angles is always 180 degrees. Therefore, we can write the equation:
![\[ \angle A + \angle B + \angle C = 180^\circ \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/ufn79ojg2j3ct4bh2rl51yc7gv44jij6ww.png)
Now, substitute the given angle measures:
![\[ (3x) + (3x + 10) + (4x - 30) = 180^\circ \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/i18m5v6xm8vmpkgd5dkb4tvjiihmj4jhci.png)
Combine like terms:
![\[ 10x - 20 = 180^\circ \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/38m1883mjmnfo5nrrroeeudevg1t2dlokj.png)
Add 20 to both sides:
![\[ 10x = 200^\circ \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/920dqwo997d667hqua8h9ol77cy3bsbxp2.png)
Divide by 10:
![\[ x = 20^\circ \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/302zm7bagxbqpsms9wvx1j772h0a1oz19g.png)
Now that we know the value of x, we can find
:
![\[ \angle C = 4x - 30 = 4(20) - 30 = 50^\circ \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/1p9vs4csememd54a23lwbktf624vkjzutn.png)
So, the measure of
is 50 degrees. The answer is D. 50°.