If you round each decimal to the nearest tenth it would be 26.7 + 89.4 because you round up if it is 6 and above and round down for 5 and below. The rest is just simple addition.
Using Pythagoras Theorem, (b is the length of the ladder from the ground) 11x11=6x6+(b^2) 121-36=(b^2) 85=(b^2) b= 9.219544457292887 b is approximately 9.2