18 is 45% of what numbet

18 is 45% of a number
18 is 45% of x
18 = 45% of x
18 = 0.45 * x

Now, to isolate x, you divide both sides of the equation by 0.45.

18 / 0.45 = 0.45*x /0.45
x = 40

So, 18 is 45% of 40. Hope this helps! :)

Part/Whole=Percent/100
Part=18
Percent=45
Whole= a variable that we are trying to figure out
so now its 18/x=45/100
Cross multiply and get 
45x=1800
Divide by 45 and get 40. 18 is 45%of 40

2% compounded quarterly is .5% each quarter  (2% ÷ 4) 
So the principal (200) is multiplied by  1.005 ⁸  (8 because there are 8 quarters in 2 years)

200 x 1.005 ⁸ = $208.14 in 2 years (rounded to the nearest penny)

4% over 12 months is 1/3% every month  or .003333
200 x 1.00333²⁴  (24th power since there are 24 months in 2 years) $216.61 in 2 years rounded to the nearest penny.
The monthly scenario is better.