Answer:
X = 14
Explanation:
First you want to look at the scale ratio to find what the length actually is. So B is 7 times larger then A. So then you want to divide the length of B's side by 7 to find the actual size of As.
28 / 7 = 4
So now that you know the actual length is 4 you can write it into the following equation,
x - 10 = 4
Then you just solve for X
x - 10 = 4
+10 +10
x = 14