To find the Mean or Average you have to add up all numbers it is asking for which in case are 222 and 198.
so you will add 222+198
That will equal 420
Then you will divide with the amount added together which is 2
420/2=210
so the mean of the 11 people is 210 or 210lbs
X sqrd-4x+y sqrd-10= -29
y sqrd-10y = -29-X sqrd + 4X
y(y-10) = -29-X sqrd +4X
y = - 29 -X sqrd +4X ÷( y- 10)