170 cm. The unknown length on the left is 21 cm
The formula for point-slope form is y-a=m(x-c), where y and x are variables, a is simply one point in y, m is the slope, and c is simply one point in x. The first thing we can find is m, or the slope. This is found by dividing the change in y over the change in x. The equation for this is (I’ll plug the points in the equation)

Therefore, our answer is the bottom one as our slope is 1/4.
Feel free to ask further questions!
The Answer to the question is:
5/4
5/2