In order to write this quadratic equation in standard form, first note that standard form is ax^2+bx+c for quadratics, where c is the numerical value (constant), B is the coefficient of x, and a is the coefficient of x^2 and is the leading coefficient. Next, multiply the binomials of (x-7) and (x-1). You can do this by using FOIL, or by distributing each of the terms in a binomial to each of the other terms in the other binomial. (Please let me know if you need a walk through in this step in particular). Furthermore, you should then write y= (the simplified trinomial). Now, the quadratic is in standard form. To reiterate, just simplify the two binomials by multiplying them together and writing that they're equal to y.
If it takes eight men ten hours, it would take seven men nine hours, six men eight hours, five men seven hours and that brings us to the answer you need. It would take four men six hours.
