The perimeter is 38.4 inches
6 multiplied by negative 7 would be negative 42. Negative 42 added by negative 8 would be negative 34.
Step-by-step explanation:

The answer is 14. This is because 63=3+x+3x-4. Then You just subtract it and then you get 64=4x. Then you just divide it and then you get x=16.