If log 5 = x, find the value of log 625.
x/4
4x
3x
5x
log 625 = log 54
log 625 = 4 log 5
log 625 = 4x
If x=1+log 2−log 5, y=2 log 3 and z=log a−log 5; find the value of a, if x+y=2z.