For this case we have to:
x: Let the variable representing the number of people to travel in the group
y: Let the variable representing the number of miles traveled.
If friends only have $22 then we have the following inequality:
[tex]2.50x + 0.75y \leq22[/tex]
Now, if there are three people in the group we have that [tex]x = 3.[/tex]
[tex]2.50 (3) + 0.75y \leq22\\7.5 + 0.75y \leq22\\0.75y \leq22-7.5\\0.75y \leq14.5\\y\leq \frac {14.5} {0.75}\\y\leq19.33[/tex]
The taxi can travel a maximum of 19.33 miles.
On the other hand, if the group wants to travel 10 miles then we have to y = 10.
[tex]2.50x + 0.75 (10) \leq22\\2.50x + 7.5 \leq22\\2.50x \leq22-7.5\\2.50x \leq14.5\\x\leq \frac {14.5} {2.50}\\x \leq5.8[/tex]
Thus, they could travel a maximum of 5 people.
ANswer:
[tex]2.50x + 0.75y \leq22[/tex]
Traveling 3 people, the taxi can travel a maximum of 19.33 miles
Traveling 10 miles, a maximum of 5 people can travel