Arwin earns Rs 1200 per month, he spends \[\frac{\mathbf{1}}{\mathbf{4}}\] of his income on food, \[\frac{\mathbf{3}}{\mathbf{10}}\] of the remaining money on house rent and \[\frac{\mathbf{5}}{\mathbf{21}}\], of the remaining money on the education of his children. How much money does he save in a month?

• A. Rs. 450
• B. Rs. 420
• C. Rs. 400
• D. Rs. 480