A graphing calculator quickly graphs both lines and computes their intersection to decimal accuracy. Solving by hand with these decimals is slower and prone to arithmetic errors. A spreadsheet is not ideal for solving two equations graphically, and mental estimation cannot deliver coordinates to the nearest hundredth.

Mental estimation is fastest and sufficient: compare unit prices by rounding and cross-multiplying. For example, $4.59\times 28\approx 4.6\times 28=128.8$ and $5.19\times 24\approx 5.2\times 24=124.8$, so the 28 oz option is slightly cheaper per ounce. A calculator or spreadsheet is slower for an aisle decision, and paper-and-pencil is unnecessary.

Paper-and-pencil algebra lets you clear fractions and isolate $x$ to get an exact value without rounding. Mental estimation will not be precise. A graphing calculator could approximate by graphing two lines but adds setup and may not give an exact fractional answer. A spreadsheet does not handle symbolic manipulation cleanly here.