Answer:
Step-by-step explanation:
- 3r - 4s and 4s - 3r is not correct because subtraction is not communitive
- 3(4r) and 7r may look right, but it is not 3+4 and instead is 3x4 = 12. 12 ≠ 7
- 3r + 4r and 7r is correct! 3 plus 4 is 7 and they all have r creating like terms and being able to be added together
- r + r + r and r³ is incorrect because r + r + r = 3r, not r cubed
