Answer:
2(x+10) = 3x-30 (reason: vertical angles are congruent)
2x+20 = 3x-30
20 = 1x-30
1x = 20+30
1x = 50
x = 50
The formula required is:

where A is the amount after t years of the principal P invested at an annual interest rate r (expressed as a decimal fraction) compounded n times per year.
Plugging in the given values, we get:

The final amount is $22,096.17
Okay so you have 10/12 marbles (ten out of twelve). Both 10 and 12 can be divided by 2, right? So divide both of those by 2 and you get 5/6. That’s your answer. Hope this helps!