a=1, 2, 3, 4
b= 1, 2, 3, 4, 5, 6
c= 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
d= 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44
x= 3/14
y= 13/16
z= 5/12
w= 17/24
