Its simple. You collect like terms and put them on one side of the equation
Apparently, the calculator at the link in your lesson is fully capable of giving you the necessary numbers. My own TI-84 work-alike gives me the account balances, but the rest of the numbers need to be figured.
In 30 years, there are 12×30 = 360 months, or 4×30 = 120 quarters. See the calculator results below. Your table can be filled in using the given information to find the contribution amount. The calculator gives the final balance. The interest amount is found by subtracting the contribution amount from the final balance.

Answer:
48
Step-by-step explanation:
55+65=120 and 2/5 of 120 is 48
Answer:

General Formulas and Concepts:
<u>Algebra I</u>
<u>Calculus</u>
Antiderivatives - integrals/Integration
Integration Constant C
U-Substitution
Integration Property [Multiplied Constant]: 
Trig Integration:
Step-by-step explanation:
<u>Step 1: Define</u>
<u />
<u />
<u />
<u>Step 2: Integrate Pt. 1</u>
- [Integral] Factor fraction denominator:

- [Integral] Integration Property - Multiplied Constant:

<u>Step 3: Identify Variables</u>
<em>Set up u-substitution for the arctan trig integration.</em>

<u>Step 4: Integrate Pt. 2</u>
- [Integral] Substitute u-du:

- [Integral] Trig Integration:
![\displaystyle \frac{1}{9}[\frac{1}{\frac{2}{3}}arctan(\frac{u}{\frac{2}{3}})] + C](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cfrac%7B1%7D%7B9%7D%5B%5Cfrac%7B1%7D%7B%5Cfrac%7B2%7D%7B3%7D%7Darctan%28%5Cfrac%7Bu%7D%7B%5Cfrac%7B2%7D%7B3%7D%7D%29%5D%20%2B%20C)
- [Integral] Simplify:
![\displaystyle \frac{1}{9}[\frac{3}{2}arctan(\frac{3u}{2})] + C](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cfrac%7B1%7D%7B9%7D%5B%5Cfrac%7B3%7D%7B2%7Darctan%28%5Cfrac%7B3u%7D%7B2%7D%29%5D%20%2B%20C)
- [integral] Multiply:

- [Integral] Back-Substitute:

Topic: AP Calculus AB
Unit: Integrals - Arctrig
Book: College Calculus 10e