Please help Im struggling a bit

Solve the system of equations. y= 2x y= x^2 - 15

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.

Zack and tia played chess for 50 min they put the chessboard away at 11: 20 when did they start