Answer:
x = 8
Explanation:
The perimeter of a body is the sum of all its sides.
Perimeter of the triangle;
hypothenuse + opposite + adjacent = x+6 + x + 3 + x + 9 = 3x + 18
Perimeter of the rectangle = x+1 + x + 4 + x + 1 + x + 4 = 4x + 10
Now,
Since their perimeter is equal;
3x + 18 = 4x + 10
3x - 4x = 10 - 18
-x = -8
x = 8