Answer:
B, 20
Explanation:
The Pythagorean Theorem states that the two shortest lengths in a right triangle (in our case, 12 and 16), is equal to the longest length in a right triangle (c). So,
a²+b²=c²
Substitute 12 and 16 for a and b, our side lengths
12²+16²=c²
144+256=400
400=c²
Square root both c and 400, which gives us...
20=c
So, the value of x is 20.