Q40. - Algebra 2

Question

STAMPS For Exercises 39 and 40, use the following information.

The table shows the price for first-class stamps since the U.S. Postal Service was created on July 1, 1971.

40. Predict the price for a first-class stamp issued in the year 2010.

Step-by-Step Solution

Answer

The price for the first -class stamp in the year 2010 is $\$ \backslash [86.57.\backslash ]$

Step-1 – Concept of solving two equations by graphing

To graph of a linear inequality in two variables$\left(xandy\right)$, first get$y$alone on one side. Then consider the related equation obtained by changing the inequality sign to an equality sign. The graph of this equation is a line. If the inequality is strict $\left(<or>\right)$ graph dashed line. 

Step-2 &ndash;Write the prediction equation of the graph

We know that the prediction equation of the graph is$7y-15x=21.$

Step-3 &ndash;Price of the first-class stamp issued on the year 2010

 In 2010, the age of U.S Postal service is $39.$

Substitute $x=39$ in prediction equation.

$\begin{array}{l}7y-15\left(39\right)=21\\ 7y=21+585\\ y=\frac{606}{7}\\ y=\mathrm{86.57.}\end{array}$