The first problem you can use the pythagorean theorem. To get the equation:7^2 + X^2 = (X+1)^2
Then, if you expand.. you get 49 + X^2 = X^2 + 2X + 1
Simplify to get 49 = 2X + 1
Then solve to get X= 24
You might want to note that this is a special 7,24,25 triangle.
For the second problem, you might want to set up proportions because they are similar figures.
ex. (8/12)= (6/X)
Then you'll easily get the answers and find the perimeter. I think....