i see you @Eagle Mum. tell your boy to try this 50-60-70 q. the 60 one is straight forward enough 50-60-70 should be aimo level or higher and im too rusty.
Take any equilateral triangle and pick a random point inside the triangle. Draw from each vertex a line to the random point. Two of the three angles at the point are known let's say $x$,$y$. If the
Suppose that PQR is a 50-60-70 (respectively) triangle with an interior point X. Let angle PXR = s and angle QXR = t.
Find (in terms of s and t) the three angles of any triangle with side lengths equal to PX, QX and RX.