There is another way to it also,
Remember, the formulae for sum of consecutive even numbers is n(n+1)
eg: sum of 2,4,6,8,10 (which are five consecutive even number is n=((2+10)/2))-1)=5, where 2 is the first number in the series & 10 is the last number therefore n(n+1)=5*(5+1)=30)
Apply the formulae here. The sum of consecutive even number till 180 is n(n+1)=90*91=8190, where ((n=2+180)/2)-1=90
The sum of consecutive even number till 120 is n(n+1)=60*61=3660
Take the difference of the sum 8190-3660+120=4650. (Remember while deducting the two sums we r also reducing 120 frm the sum which has to be added back.
Here we got the value of x=4650.
Now y=(180/2)-(120/2)+1=31 (Here we have to add 1 back because we have excluded 120 while calculating the difference. Remember x/y=z implies there are z multiples of of y between 0 & x).
Therefore we get x+y=4650+31=4681