JAMB 2012 · UTME · Q25

In the diagram, $QR \parallel TU$ , $\angle PQR = 80^\circ$ and $\angle PSU = 95^\circ$ . Calculate $\angle SUT$ .

Worked solution (try it first)

Draw a line through $S$ parallel to $QR$ and $TU$ .
By corresponding angles, $SP$ makes $80^\circ$ with it, the same as $\angle PQR$ .
$\angle PSU = 95^\circ$ , so $SU$ lies $95^\circ - 80^\circ = 15^\circ$ beyond the parallel line.
By alternate angles with $TU$ , $\angle SUT = 15^\circ$ , option A.