Yes it is a function any single value of x has only one value of y
Month 1
Sister 1; 60/ Sister 2; 60
Month 2
Sister 1; 80/ Sister 2; 60
Month 3
Sister 1; 100/ Sister 2; 100
On month 3 the should both have $100 in their accounts.
Answer:

Step-by-step explanation:
Given



Required
Determine the invested amount
First, we need to determine the Principal
This is calculated as:

Solve for Principal




Add the principal to the interest



Answer:
The average expenditure is $4586.32
Step-by-step explanation:
January: $5,678.54
February: $3,665.77
March: $4,231.98
April: $4,768.99
The average monthly expenditure is the sum of all expenditures computed/number of months
Jan+Fev+Mar+Apr/4 = 5,678.54 + 3,665.77 + $4,231.98 + $4,768.99/4 = 18,345/4 = 4586.32
So, the average expenditure is $4586.32