The leading term of a polynomial is the term with the largest exponent, which in this case that exponent is 4. So the leading term is -3x^4.
The leading coefficient is the coefficient of the leading term. The coefficient of the term -3x^4 is -3.
If the polynomial is written in standard form, then the process is as simple as reading the first coefficient. Otherwise, you may have to sort the terms out first.
X = one number 125 - x = other number 5x - 3(125 - x) = 41 ==> 5x - 375 + 3x = 41 ==> 8x = 416 ==> x = 52, one number, and 125-52 = 73, the other number.
