1. **State the problem:** Elizabeth's subtotal is $x$ dollars. A tax of 6% is added, and then a tip of 21% is applied to the total after tax. We need to find an expression for the total amount paid. 2. **Write the tax amount:** Tax is 6% of $x$, so tax = $0.06x$. 3. **Calculate the total after tax:** Total after tax = subtotal + tax = $x + 0.06x = 1.06x$. 4. **Calculate the tip amount:** Tip is 21% of the total after tax, so tip = $0.21 \times 1.06x = 0.2226x$. 5. **Calculate the total amount paid:** Total paid = total after tax + tip = $1.06x + 0.2226x = 1.2826x$. 6. **Final expression:** $$\text{Total paid} = 1.2826x$$ This means Elizabeth pays 128.26% of the subtotal $x$ including tax and tip.