Answer:
f(9)=-2
Step-by-step explanation:
f(9)= -9+7= -2
3x - 2x + 4 = 5x - 4x - 8
First, let's focus on the left side of the problem (3x - 2x + 4). Let's subtract 3x - 2x which will get us 1, and since a variable by itself is considered 1, we can just put the variable.

Second, now let's focus on the right side of the problem (5x - 4x - 8). Subtract 5x - 4x to once again get 1. Replace it with the variable and leave the rest.

Third, we can now cancel out x on each side. This will leave us with 4 = -8, which is false, meaning that there is no solution to this problem.
All you have to do is plug in the value of X in each expression for the sides of the triangle. Then after you figure out the values for the sides of the triangle in feet. Add the sides together to find the perimeter of the triangle.
Step-by-step explanation:
=2b+9
=2×3+9
=6+9
=15
hope it helps.