A rectangle has a length of (3x - 4) units and a width of (2x + 3) units.

Hint: 

We know that the perimeter of a rectangle is \(2*(length+width)\) -why? (The perimeter is the sum of the outer lines of a figure, I.e. not the inside unlike area, so we add all lines)  Since rectangle has 2 lengths and 2 widths thus adding a length and a width and multiply it by 2 is  a correct formula.

Solution

given length=3x-4

given width=2x+3

Finding perimeter is just applying the rule,

2(3x-4+2x+3)

simplify the bracket

2(5x-1)=10x-2 

So C. is the correct choice.

Remember that the formula for perimeter is 2L+2W. In this case, that would be 2(2x-4)+2(2x+3). If you add those numbers, you get the perimeter as 10x-2. So, the answer is C.