Answer:
3
Step-by-step explanation:
3 is a prime number so other than 3x1 3 does not have any other factors
r = -1/2
3(5 + 4r) = -18r
15 +12r = -18r by distributive property
15 = -12r - 18r
15 = -30r
r = - 1/2r
Answer: look at the picture
Step-by-step explanation: Hope this help :D
