Question

A book costs $12. If you have y dollars, write an equation to find out how much more money you need to buy the book if you currently have $5. Write the equation

Answer 1

To find out how much more money you need to buy the book if you currently have $5, we start with the cost of the book, which is $12. You currently have $5.

Let the variable represent the additional amount of money needed, which we can denote as \( x \). The equation that represents how much more money you need can be written as:

\[
5 + x = 12
\]

To solve for \( x \), you would subtract 5 from both sides:

\[
x = 12 - 5
\]

So, the equation is:

\[
x = 12 - 5
\]

Which simplifies to:

\[
x = 7
\]

This means you need an additional $7 to buy the book. If you want an equation that includes \( y \), where \( y \) is the amount of money you currently have (in this case, \( y = 5 \)), you could write:

\[
y + x = 12
\]

Thus, substituting \( y \) into it gives:

\[
x = 12 - y
\]

And when \( y = 5 \), you would again find:

\[
x = 12 - 5 = 7
\]

So the equation to find how much more you need given any amount \( y \) is:

\[
x = 12 - y
\]