Answer:
A and C
Step-by-step explanation:
The first choice is correct, this is because ∠1 + ∠2 = 180 - ∠3, and to calculate ∠4, you would also do this calculation.
∠1 + ∠2 = ∠4
The second choice is incorrect because anything being added to ∠3 will make ∠4 too big.
The third choice is also correct, this is because it is the equation to calculate ∠4 by subtracting ∠3 from 180. Now we know the two correct equations.
Hope this helps!
