George found that he blinked 85 times in 15 minutes at this rate how many minutes pass during 51 blinks math

Since they blink at the same rate, the number of blinks per minute must be equal between the two periods of time. Therefore,

85 blinks / 15 minutes = x blinks per minute
51 blinks / y minutes = x blinks per minute

Since the rates are equal, you can set these two proportions equal to each other.

85 blinks / 15 minutes = 51 blinks / y minutes

85 * y = 51 * 15

y = (51 * 15) / 85 = 9 minutes

So 85 is to 15 mins
85:15
85/15=17/3
17:3=51:x
17/3=51/x
multiply both sides by 3x to clear fraction
17x=153
divide both sides by 17
x=9
9 mins passed

The scale factor of what ?