Subtracting a number is the same as adding its opposite. this understanding to complete each of the equations below.

Asap! i'm not good math and i'm lost.

The graph of a function f(x)=(x+2)(x-4). which describes all of the values for which the graph is negative and increasing? all real values of x where x< -2 all real values of x where -2

Given sin28.4=.4756, cos28.4=.8796, and tan28.4=.5407 find the cos of 61.6