So,
Miss Hoffman gave 90 cents to the waitress.
Her meal, including the tip, cost $6, or 600 cents.
Her subtotal was represented by the quantity (600 - 90) cents.
600 - 90 = 510
Dividing 90 by 510 yields the percent tip that Miss Hoffman gave the waitress.
[tex] \frac{90}{510} [/tex]
[tex] \frac{9}{51} [/tex]
0.176 or 17.6% ≈ 18%
Miss Hoffman gave the waitress approximately 18% tip.
