I we consider her running times as an arithmetic series with common difference:
43.13 - 43.1 = -.03/2 = -.015, Shelly's time in the fourth race will be 43.1 - .015 = 43.085.
You must factoring the number 192, you will get 192=2^6*3, so you have square root(2^6*3)=2^(6/2)*root(3) applying enhancing property.
Solve the exponent and you get =2^3*root(3)= 8*root(3)
Y=2 7x2= 14
X= 7 4x7=28
28-14=14