please help ASAP

This triangle is equilateral....so....all sides and angles are equal

So

2y  = 25x - 15    add 15 to o both sides

2y + 15   =  25x     divide both sides by 25

[ 2y + 15 ] / 25    = x

So, it would be 27.5? 

Sorry.....If you want a numerical answer... note that all the angles = 60°....so.....

25x - 15  =  60     add 15 to both sides

25x  =  75      divide both sides by 25

x  = 3