A={x:x2−5x+6=0}
x2−5x+6=0
⇒(x−2)(x−3)=0
⇒x=2,3
⇒A={2,3}
B={y:y∈Z,3<|y−2|≤5}
3<|y−2|≤5
Case :1 When y≥2
3<y−2≤5
⇒5<y≤7
Case :2 When y<2
3<2−y≤5
⇒1<−y≤3
⇒−3≤y<−1
Since y∈Z,
y=−3,−2,6,7
⇒B={−3,−2,6,7}
Number of relations from A to B is 2n(A)⋅n(B)=22⋅4=256