Answer: 40%
Explanation:
Number of guests that yesterday called for room service = 170
Number of guests that did not call for room service = 255
Total number of guests = 170 + 255 = 425.
The percentage that call for room service = Those that call for room service / Total guest × 100
= 170/425 × 100
= 0.4 × 100
= 40%