Answer: 35.
Key: a+ b = 5 (a + b)
2 + 3 = 5 * (2 + 3) = 25.
4 + 5 = 5 * (4 + 5) = 45.
0 + 8 = 5 * (0 + 8) = 40.
Similarly,
1 + 6 = 5 * (1 + 6) = 35.
Z(x.y)=5(x+y) Z(1,6)=35