To find the whole when a fraction of it is known: divide by the fraction (multiply by its reciprocal). Then find the required fraction of the whole.

Step 1: Find the original number. If 3/4 of it is 27, then the number = ?
Whole number	=	\(27 \div \dfrac{3}{4} = 27 \times \dfrac{4}{3} = 27 \div 3 \times 4 = 9 \times 4 = 36\)
Step 2: Find 11/18 of this number.
\(\dfrac{11}{18}\) of 36	=	\(36 \div 18 \times 11 = 2 \times 11 = 22\)