Answer:
The maximum number of guests for $780 would be 26.
Step-by-step explanation:
Write and solve an equation of ratios. In the first column write $630/$780; in the right column write 21/x:
630 21
---------- = -------
780 x
Cross-multiplying, we get 630x = 21(780), which yields x = 26.
The maximum number of guests for $780 would be 26.
