For set A:
∣(∣x−3∣−3)∣≤1⇒2≤∣x−3∣≤4.
If x≥3: 5≤x≤7⇒x∈{5,6,7}.
If x<3: −1≤x≤1⇒x∈{−1,0,1}.
So A={−1,0,1,5,6,7}, ∣A∣=6.
For set B:
x−1(x−2)(x−4)loge(∣x−2∣)=0 with x∈R−{1,2}.
Either x−1(x−2)(x−4)=0⇒x=4 (since x=1,2), or loge∣x−2∣=0⇒∣x−2∣=1⇒x=3 (since x=1).
So B={3,4}, ∣B∣=2.
Number of onto functions from A to B =26−2=62.