The slope is the rise over run or the change in y over the change in x. In this case, the y decreases by 3 while the x increases by 1. Since one value increases while the other decreases the slope must be negative. So if we put the 3 over 1 and make it negative the answer is -3/1, which simplifies to -3.
Separate the polynomial into two groups of two terms and factor out the common value from each group. If the values factored out from each group are the same, then you can use the grouping method. The factors will be the outside terms and the common factor.