Answer: The answer is 79.0°
Explanation:
A quadrilateral will always have 360° and four sides. Keep that in mind, that's a universal rule of geometry.
Here, the sum of all sides is equal to 360°. Therefore, we make an equation:
![(14x-11) + (8x+7) + (5x+18) + (10x + 13) = 360](https://img.qammunity.org/2021/formulas/mathematics/high-school/lpaf7ts2vldz13l2lvpi1hcxkzu7kew7kp.png)
Simplify by adding and subtracting like terms.
![37x +27=360](https://img.qammunity.org/2021/formulas/mathematics/high-school/b9q77vwbeq1stiswzmi1mr30a5vrduin20.png)
Isolate x by first passing the 27 to the other side.
![37x = 333](https://img.qammunity.org/2021/formulas/mathematics/high-school/mse5vh833nhy0qarw5jz830b9pqhcxvj9p.png)
Divide by 37 to isolate x.
![x = 9](https://img.qammunity.org/2021/formulas/mathematics/high-school/1z5wn7xt3xwszwug4q2n18sz851or739mc.png)
To find m∠B, we plug in x to
![(8x+7)](https://img.qammunity.org/2021/formulas/mathematics/high-school/aylklrjxs93kify312p7oqfzbzd27bcrt0.png)
which gives you:
![(8*9+7) = 79](https://img.qammunity.org/2021/formulas/mathematics/high-school/31a1moq2x4o4i248vy5izl8bqf3oo1e47n.png)
The answer is 79.0°
Curious if it is correct? Let's double check.
Plug in the x=9 to all the x values and add them up. You should get 360, which makes the answer correct.