'O' Levels E Mathematics Problem

Having a bit of problem here. Asked around with quite a number of schoolmates, none could solve it.

Question 10a. 10b is easy to solve once 10a is done with.

Answer for 10a is 42 degrees.

Thanks for reading.

Its not really too hard.

1) Find PTS

2) Find PST

3) PST = PTQ (forgot whats the name of the rule) alt segment theorem?

Ah. Didn't think it would apply there. Thanks for the help.

did a mistake lol