Looking at Triangle WYZ, 3^2 + 4^2 = c^2 … 9 + 16 = 25 = c^2 so c = 5
Looking at triangle WYX, 4^2 + a^2 = b^2 …
Looking at triangle WXZ, 5^2 + b^2 = (a + 3)^2
Substitute 2nd equation into 3rd equation for b^2
25 + (16 + a^2) = a^2 +6a + 9
41 + a^2 = a^2 + 6a + 9
- a^2. -a^2
-9. -9
32 = 6a
/6. /6
32/6 = a
16/3 =a