Hello there! I can help you! For this problme, we are looking for the value of r. First off, let's combine like terms. 7r amd 2r are like terms, because they have the same variable. 7r - 2r is 5r. The expression shortens to 5r = 15. Now, divide each side by 5 to isolate the r. 5r/5 cancels out. 15/5 is 3. Let's plug in 3 as r to see if this works. 7 * 3 is 21. 2 * 3 is 6. 21 - 6 is 15. There's out answer. r = 3.
