Here's the translated financial problem:If you want to receive an annual salary of $100,000$ SAR per year for $20$ years starting from the date of your retirement, assuming retirement begins at age $60,$ and your current age is $25,$ how much should you invest monthly in an investment account that yields an annual return of $10\%$ from now until retirement? Note that the interest rate during the retirement period is $12\%$ and will continue from the beginning of retirement until the end of the $20$ years.