Using the equations y-3x=3 and x+y=31 you can find that x=7 and y=24. There for x is the smaller of the two numbers.
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.
