The answer would be 10 11/20 or 10.55 in decimal form
8 1-and-a-half blocks would be 12 blocks, and so 12/17, because 12 blocks in 17 mins., so you divide 12 by 17 to get ---- blocks per minute, which is 12/17 as a fraction, or approx. 0.705882353 blocks per minute.
Let the number be x.
6x-20=94
6x=114
x=19
