Concept:Percentage means part per hundred. To find the whole number, divide the given part by the percentage expressed as a decimal.Explanation:Let the unknown number be N.5% of N equals 22.50.Write 5% as 1005​ or 0.05.So, 0.05×N=22.50.Divide both sides by 0.05: N=0.0522.50​.Calculate: N=450.Answer:Option A: 450.