Answer:
The initial value is $78
Step-by-step explanation:
Given

(weekly)
Required
Determine the initial value
The initial value is the amount he has in its bank account before making his weekly savings.
From the question, we have that his initial balance is $78.
Hence, the initial value is $78
However, his weekly balance can be expressed as:

Represent number of weeks with x; So, we have:


Well it's 4 time the radius, so 4r
And it's 3 less than that, so
4r - 3 is the height
Let the number of children be c, and the number of adults be a.
c + a = 170 (total number of tickets)
Then the cost of each is: $5.90/child, $9.60/adult:
5.9c + 9.6a = 1269.40 (total sales)
Solving as 2 simultaneous equations, we first transform the first equation:
a = 170 - c
Substitute into the 2nd equation:
5.9c + 9.6(170 - c) = 1269.40
Solving gives c = 98, and a = 170 - 98 = 72. This means that 72 adult tickets were sold that day.
The 25th arithmetic term will be -67