I need help with number 10 please

Answer:
18x-10 (I think)
Step-by-step explanation:
Since the perimeter is all the sides of the rectangle (4) added together, that is all you have to do. 6x + 6x = 12x, 3x-5 + 3x-5 = 6x-10, and those two answers added together get you 18x-10.