two angles across from each other at a junction, are vertical angles, and therefore twins.
in this case, ∡7 and her twin ∡5 are each then 2x + 15, and ∡8 and her twin ∡6 are each 3x.
keeping in mind that in a circle, there is a total of 360°, so all those 4 folks will need to sum up to 360°.
