Answer:
There were 6 guides on Sunday.
Step-by-step explanation:
Same ratio
On Saturday, 120 tourists and 18 guides.
On Sunday, 40 tourists and x guides.
Due to the same ratio:
[tex]\frac{120}{40} = \frac{18}{x}[/tex]
[tex]3 = \frac{18}{x}[/tex]
[tex]3x = 18[/tex]
[tex]x = \frac{18}{3}[/tex]
[tex]x = 6[/tex]
There were 6 guides on Sunday.