Step-by-step explanation:
I think no. C is the answer. Please let me know by comment I am wrong or right
Answer:

Step-by-step explanation:
see the attached figure to better understand the problem
we know that
In the right triangle ABC, the tangent of angle of 30 degrees is equal to divide the opposite side to the angle of 30 degrees (AC) by the adjacent side to the angle of 30 degrees (BC)

substitute the given values

Solve for b

Answer:
See explanations below
Step-by-step explanation:
Given the system of equation
2x - 10 y = -30 ... 1
x - 5y = 20 ... 2
Step: From 2;
x = 20 + 5y ...3
Step 2: Substitute equation 3 into 1
2x - 10y = -30
2(5y+20) - 10y = -30
Open the bracket
10y + 40 - 10y = -30
10y - 10y + 40 = -30
0+40 = -30
40 = -30
The steps taken by Teri are correct all through. He didn't make any error whatsoever
It would be the second one if you follow PEMDAS