To get your answer, follow my method :
First you take away 24 from 250=226
Then you half 226=113 which is Mark's weight
As Mike weights 24 pounds more that Mark, you have to add 24 back=137
So your answer is :
Mark weights 113 pounds and Mike weights 137 pounds.
Do 180 and subtract 171 so 9
The outer exponent is 4 so there will be 5 terms all together. By rules of exponents
C(4,0)(3^4)(2^0)(x^8)(y^0) + C(4,1)(3^3)(2^1)(x^6)(y^3) + C(4,2)(3^2)(2^2)(x^4)(y^6) + C(4,3)(3^1)(2^3)(x^2)(y^9) + C(4,4)(3^0)(2^4)(x^0)(y^12)
The coefficient of the 3rd term: C(4,2)(3^2)(2^2) = 6 x 9 x 4 = 216
26.916278062 is the answer