I think it's A because 35n is independent from the 50.
Triangle ABC and triangle DCE are congruent, so line DE = line AB
Use the cosine rule to find angle ACB






Angle ACB = 48.1°
Answer:

Step-by-step explanation:






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Translation in English:
Step 1 : Swap the sides of the equation
Step 2 : Divide both sides by 14
Step 3 : Calculate


~
The answer should be Step 1; 3(1+2x)-2(x+1)+5