Hi there!
First we need to remember the following.

Now substitute both of the formulas.

Work out the parenthesis.

And finally collect terms.

~ Hope this helps you!
Answer: A, C, D
If you try plugging in a few different numbers into these equations, you will get only 1 result.
:)
Answer:
×=4.2
Step-by-step explanation:
3.5x=14.7
÷3.5 ÷3.5
x=4.2
Ok so you do 900 ÷ 10 which = 90 and 90 x 10 = 900 so the answer is 90