Chapter 8.2, Problem 53IP

To determine

The number of second s it will take to download the rest of the file

Answer to Problem 53IP

  $s=8$

Explanation of Solution

Given:

Draven’s computer downloads files at a rate of 220 kilobytes per second and the computer has already downloaded the first 550 kilobytes of a 2310-kilobytes file and the equation, $550+220s=2310$

Concept Used:

• To get rid of a number in addition from one side, subtract the same number from both sides of equal sign.
• To get rid of a number in subtraction from one side, add the same number both sides of equal sign.
• To get rid of a number in multiplication from one side, divide the same number from both sides of equal sign.
• To get rid of a number in division from one side, multiply the same number both sides of equal sign.

Rules of Addition/ Subtraction:

• Two numbers with similar sign always get added and the resulting number will carry the similar sign.
• Two numbers with opposite signs always get subtracted and the resulting number will carry the sign of larger number.

Rules of Multiplication/ Division:

• The product/quotient of two similar sign numbers is always positive.
• The product/quotient of two numbers with opposite signs is always negative.

Calculation:

In order to solve the given equation $550+220s=2310$ for the variable, isolate the variable term s on one side by performing some basic algebraic operations to get rid of the other numbers and terms associated with it.

Here to isolate s on left side, first subtract both sides by $550$ and then divide both sides by $220$ and then simplify further as shown below,

  $\begin{array}{c}550+220s=2310\\ 550+220s-550=2310-550\\ 220s=1760\\ \frac{220s}{220}=\frac{1760}{220}\\ s=8\end{array}$

Thus, the solution of the given equation is $s=8$ .