Write the Expression in Terms of Sine and Cosine, and Simplify

Multiple Choice

Write the expression in terms of sine and cosine, and simplify so that no quotients appear in the final expression.
-Find $\cos ( \mathrm { s } - \mathrm { t } )$ given that $\cos \mathrm { s } = - \frac { 12 } { 13 }$ , with $\mathrm { s }$ in quadrant II, and $\sin t = \frac { 8 } { 17 }$ , with $\mathrm { t }$ in quadrant II.

A) $- \frac { 220 } { 221 }$
B) $\frac { 140 } { 221 }$
C) $\frac { 220 } { 221 }$
D) $- \frac { 140 } { 221 }$