A group of y numbers has mean x. If the numbers 3 and 5 are removed from the group, the mean of remaining(y-2) numbers remains unchanged. Find x.
xy-8 = x(y-2)
xy-8 = xy-2x
2x = 8
x = 4
This makes sense, since the two numbers removed must have the same mean as the whole bunch. Namely, (3+5)/2 = 4