Work Step by Step
We know that the sum of all of the individual lengths adds up to the overall length. Hence, it follows: $$ 12 = 4x+3(3) \\ 12 = 4x + 9 \\ 3 = 4x \\ x =.75$$
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.