n = 14
Step-by-step explanation: Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 28 Â Â Â Â Â n
the two blue triangles are similar. Â 28 is to n as n is to 7: Â =
                                                  n      7
Then, after cross-multiplying, we have n^2 = 7(28) = 196
Taking the square root of both sides yields
n = 14