A line with a length of 179.591mm needs to be scaled by what factor to get to a length of 200mm

Call the scale factor k for now

The idea is to multiply this scale factor by the old length (179.591) to get the new length (200)

So ...

(old length) * (scale factor) = new length

179.591*k = 200

k = 200/179.591

k = 1.1136415521936 << - - - this value is approximate

So the scale factor is roughly 1.1136415521936

If you need to round to say 3 decimal places, then it would become 1.114

Meaning that if you multiply the old length by roughly 1.114 you'll get the new length