You should have used a calculator.
Anyways, the answer is -7/2 or -3.5
Eleven fifteenths minus ten fifteenths is equal to one fifteenth.
11/21 (eleven over twenty-one)
decimal which is equivalent to nine over eleven = 0.8181
Since our numerical system is based upon 10 digits, every number divided by nine wil cause an infinite loop of numbers one over nine is 0.1111111... two over nine is 0.22222222... since eighth over nine is 0.888888888... nine over nine is 0.99999999... but nine over nine is 1 so in your case eleven over nine will cause a infinite loop of 1.222222222222222222... Point is an accurate decimal form of eleven over nine or any other digits over nine is impossible.
Four and five twelfths is 53 twelfths, five and eleven twelfths is 71 twelfths so answer is "minus eighteen twelfths", ie -1½ or -1.5
4/30 - -7/30 = 11/30 or eleven thirtieths. Expressed as a decimal, this is equal to 0.36 recurring (that is, 0.36666...)
The answer is eleven thirty-sixths.