\(A=\frac{11}{12}+13+\frac{12}{13}+14+\frac{13}{14}+12\)
\(A=1-\frac{1}{12}+13+1-\frac{1}{13}+14+1-\frac{1}{14}+12\)
\(A=3-\frac{1}{12}+13+\frac{1}{13}+14+\frac{1}{14}+12\)
\(A=\frac{1}{12}+12+\frac{1}{13}+12+\frac{1}{14}+12\)
\(A=\frac{143+182+164}{572}+36\)
\(A=36\frac{489}{572}\)