The CellULar cell phone company has a data plan where 2.5 GB are included for $79.00 per month. For every 10 MB (there are 1024 MB in 1 GB) over that amount, the company charges an additional $3.00. Last month, Taylor's cell phone bill was $115. How many megabytes of data was he over the limit?
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James Sousa: Solving Two Step Equations
Guidance
Now, we will compound steps to solve slightly more complicated equations that the previous concept. We will continue to undo the operations that are in an equation. Remember that order matters. To undo the operations, work in the opposite order of the Order of Operations.
Example A
Solve
Solution:
Now we need to undo two operations. Therefore, we need to get everything on the other side of the equals sign to solve for
Now, undo the multiplication. Divide both sides by 4 to solve for
Check your answer:
Example B
Solve
Solution: First, subtract 5 from both sides.
Multiplying by onehalf is the same as dividing by 2. To undo this fraction, multiply both sides by –2.
Check your answer:
Example C
Solve
Solution:
Even though this problem involves fractions, it is still solved the same way. First, add
Check your answer:
For twostep equations:
 First, undo any addition or subtraction.
 Second, undo any multiplication or division.
Intro Problem Revisit
Writing an equation for the phone bill, we have:
Taylor is 120 MB over his data limit for the month.
Guided Practice
Solve the following equations and check your answer.
1.
2.
Answers
1. Follow the steps from above. First add 7 to both sides and then multiply both sides by –6.
Check your answer:
2. Again, follow the steps. Here, we will subtract 6 and then multiply by
Check your answer:
Explore More
Solve the following equations and check your answer. Reduce any fractions.

2x−5=−17 
−4x+3=−5 
−1=x2−6 
13x+11=−2 
34=12−18x 
−18=x−5−3 
56x+4=29 
−11x+4=125 
6−x=−22 
27x+8=20 
45=−25+32x 
15−x−9=21 
1.4x−5.6=2.8 
14.4=−2.7x−1.8 
−54=16x+312
When dealing with fractions, one way to “get rid” of them is to multiply everything in the equation by the Least Common Denominator (LCD) for the entire equation. Try this technique with the following equations. We will get you started in #16.

38x−25=74 The LCD of 8, 5, and 4 is 40. \begin{align*}40 \left(\frac{3}{8}x\frac{2}{5}=\frac{7}{4}\right)\end{align*} . Distribute the 40 and solve.  @$\begin{align*}\frac{10}{3}x+\frac{3}{4}=\frac{5}{2}\end{align*}@$
 @$\begin{align*}\frac{9}{10}x\frac{1}{2}=\frac{2}{3}\end{align*}@$
 Solve #15 using the LCD method.
 Which method is easier for you to solve equations with fractions?