The interest rate is calculated semiannually which means twice a year so you do 2.4/2 which equals 1.2 so the answer is D
<h2>Steps</h2>
So the 45-45-90 triangle is considered to be a "special triangle" and has a rule with it. If the legs are x, then the hypotenuse is x√2. Since we know that the hypotenuse is 18, this means we can set up our equation as such:

From here we can solve for x. Firstly, divide both sides by √2.

Next, we want to simplify this expression and to do that we first have to rationalize the denominator. With the right side, multiply the numerator and denominator by √2:

Next, divide:

<h2>Answer</h2>
<u>In short, the length of one leg of the triangle is 9√2 cm.</u>
To put this into an equation, we can make x the amount of two year old's there are.
x+2x+2x=45
5x=45
x=9
9 two year old's, 18 three year old's, and 18 four year old's.