Haley is at the store buying some supplies for an art project. She decides to buy some colored pencils for $3.95 and a drawing tablet. The total cost of the supplies before sales tax is $6.94.

Question

Which equation could not be used to find the cost of the drawing tablet?

x = $6.94 - $3.95
$6.94 + x = $3.95
$3.95 + x = $6.94
$6.94 - x = $3.95

Answer 1

To find the cost of the drawing tablet, we can denote the cost of the drawing tablet as \( x \). The equation that represents the total cost before sales tax is:

\[ 3.95 + x = 6.94 \]

From this equation, we can rearrange it to solve for \( x \):

\[ x = 6.94 - 3.95 \]

This is a valid equation.

Now let's analyze the other equations provided:

1. \( x = 6.94 - 3.95 \): This equation is valid as it represents the cost of the drawing tablet.

2. \( 6.94 + x = 3.95 \): This equation is not valid because it suggests that the total cost would be less than the cost of the colored pencils, which is impossible. Therefore, it cannot be used to find the cost of the drawing tablet.

3. \( 3.95 + x = 6.94 \): This is the same equation we started with and is valid.

4. \( 6.94 - x = 3.95 \): We can also rearrange this to find \( x \), making it a valid equation, as it effectively suggests finding \( x \) from the total cost minus the colored pencil cost.

Thus, the equation that could not be used to find the cost of the drawing tablet is:

\( 6.94 + x = 3.95 \).