Mean is the average, mode is the number that is repeated most often and the median is the middle number. We know there are 5 numbers so, 5 is the middle as it is the median #. The mode has to appear more than once or 5 would also be a mode.
1 1 5 _ _
M = 1+1+5+x+y /5
4 = 1+1+5+x+y/ 5
4 = 7+x+y / 5
Average of 5 numbers is 4 therefore 4 times 5 = 20
20-7 = 13, what two numbers that are more than 5 equal 13? Only 6 &7.
4 = 1+1+5+6+7 / 5