You can determine the distance between the known 'endpoint' to the 'midpoint' then work the same change on midpoint
2(10.7r - 9.5) = 33.8
10.7r
this means the number is times a variable.
10.7r - 9.5 = 1.2r
2 x 1.2r = 33.8, so we need to find the value of the variable for 1.2r
the variable that makes sense to me would be approx.14.085, so 1.2r x 2 = approximately 33.8 if you round 14.085 to the nearest tenth.
so I would say it is 14.1. hope I helped you :)
