Question

Tobin is solving the equation 3(x - 1.25) = 11.25. His work is shown below.

3(x-1.25)= 11.25
3x-3.75= 11.25
3x-3.75+3.75= 11.25+3.75
3x = 15
3x-3=45.3
X= 135
What mistake did Tobin make?

Answer 1

Answer: In the last steps, instead of multiply each side by 3, he has to divide each side by 3.

Explanation:

Hi, Tobin makes the mistake in the last steps.

3(x-1.25) = 11.25

3x-3.75= 11.25

3x-3.75+3.75= 11.25+3.75

3x = 15

Until this step is the work ok.

Now, instead of multiply each side by 3, he has to divide each side by 3:

So:

3x /3 = 15/3

x = 5

Feel free to ask for more if needed or if you did not understand something.