Answer 1

A₄ = {x : x is a two digit number and sum of digits of x is 7}

∵ x is a two digit number and sum of digits of x is 7

∴ x = 16, 25, 34, 43, 52, 61, 70

∴ Given set in roster (Tabular) form is 

A₄ = {16, 25, 34, 43, 52, 61, 70}