Final answer:
True, Jack can deduct his contributions to RPP and RRSP from his total income to calculate his taxable income, subject to contribution limits and other tax rules.
Step-by-step explanation:
If Jack has total Registered Pension Plan (RPP) and Registered Retirement Savings Plan (RRSP) contributions of $9000, it is true that he can deduct that amount from his total income to calculate his taxable income. This is how RPP and RRSP accounts are designed to work in Canada, as they are tax-deferred savings vehicles intended to encourage saving for retirement. However, it is essential to note that there are limits to how much can be contributed and deducted in a given tax year and these limits are based on one's earned income and any pension adjustments, among other factors.