Her estimate is lower than her actual cost because her total is 72.87 she is off by 1.72 because she only added 42,17,and 12 and forgot all about adding the cent or the .60,.38,and the .89.
11.9 would be the correct answer I believe
The shortcut is the hypotenuse of a right triangle with legs 6 and 8, so 6²+8²=c²
36+64=c
100=c²
c=10.
so he traveled 6+8+10=24km
Measures of angles 2, 3, 4, added equal 180