P completed 52 of the work in 12 days.
Q completed the remaining part.
Remaining work =1−52=53
Q completed 53 of the work in 18 days.
P's work rate per day:
=122/5
=52×121
=602
=301 of the work per day
P alone can complete the entire work in 30 days.
Q's work rate per day:
=183/5
=53×181
=903
=301 of the work per day
Q alone can complete the entire work in 30 days.
Combined work rate when P and Q work together:
=301+301
=302
=151 of the work per day
Days needed to complete the work together:
=1511
=1×15
=15 days
Therefore, P and Q working together can complete the work in 15 days.