Which equations shows the substitution method being used to solve the system of linear equations?
x + y = 6
x = y + 5
a. x + y = y +5
b. (y + 5) + y =6
c. x + (y +5) = 6
d. x = (x - 6) + 5

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.