Answer:
90
Step-by-step explanation:
Partition the figure by extending the sides of the ``middle'' square as shown at the right. Each original square contains four $3 \times 3$ small squares. The shaded figure consists of ten $3 \times 3$ squares, so its area is $10 \times 9 = \boxed{90\text{ square
units}}$.
Answer:
The balance in the account after 20 years will be $11280.
Step-by-step explanation:
This is a simple interest problem.
The simple interest formula is given by:

In which E are the earnings, P is the principal(the initial amount of money), I is the interest rate(yearly, as a decimal) and t is the time.
After t years, the total amount of money is:
.
In this problem
We want to find T, when 
The first step is find the earnings due to interest. So

Adding to the principal to find the balance

The balance in the account after 20 years will be $11280.
Answer:
35
Step-by-step explanation:
40=1/2(115-x)
80=115-x
-35=-x
x=35
25% = 0.25
40 / 0.25 = 160
40 is 25% of 160.
There are 160 children in the club.