Anyone know how to do this?

A) 12

Step-by-step explanation:

Yes you have to do a² + b² = c²

So the bottom triangle is 3 and 4 so plug in.

4² + 3² = c² (simplify)

16 + 9 = c²

25 = c² (square root both sides)

5 = c

That gives us the vertical side of the second triangle.

So plug in again

5² + b² = 13² (simplify)

25 + b² = 169 (subtract 25 on both sides)

b² = 144 (square root both sides)

b = 12

x = 12

Hope this helps ya!!

B

Step-by-step explanation:if it's a negative 3/4x then in be there is a -4 and there is a -7 so we can do -7 -4 but 4 is a negative so it turns into a positive so it's _

-7+4 and it become a smaller negative so -7+4 = -3. So it has to be B. Hope this gets brainliest