Can't see the full question :/
Answer:
Step-by-step explanation:
You know that 9 = 10 - 1.
Then 9 of something is equal to 10 of it less one of it. Here, that "something" is four.

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<em>Comment on this math</em>
This illustrates a shortcut for multiplying by 9 that can be convenient for mental arithmetic. The idea is to multiply by 10, which just involves adding 0 (or moving the decimal point), then subtract the original number.
Answer:
The answer is D.
Step-by-step explanation:
You have to divide it by 2 :
∠RST = ∠ROT ÷ 2
= 46° ÷ 2
= 23°
O represents the centre of circle.
(Correct me if I am wrong)