Respuesta :
The minimum number of hours he can spend cleaning the table is 2 hours
Here, we want to calculate the minimum number of whole hours clearing tables that must be worked
Let the number of hours spent lifeguarding be l, while the number of hours spent clearing tables be t
The total number of hours is 19 hours maximum
Thus, we have it that;
[tex]l\text{ + t}\leq\text{ 19}[/tex]Secondly, he must earn a minimum of $270
So, if we have the product of the number of hours and the payment per hour for each job, the amount must be at least $270
Mathematically, we have this as;
[tex]18l\text{ + 9t }\leq\text{ 270}[/tex]From the question, we are told that he spent 14 hours life-guarding
Since the total number of hours cannot be greater than 19, it means that the number of hours spent cleaning the table is between 1 and 5 (maximum)
Now, let us use these values and see if the arrangement will work
We plug the value of 14 for the number of hours spent lifeguarding into the second equation, while we switch values for the number of hours spent cleaning tables from 1-5
We have this as;
[tex]\begin{gathered} 18(14)\text{ + 9(5) = 297} \\ 18(14)\text{ + 9(4) = 288} \\ 18(14)\text{ + 9(3) = 279} \\ 18(14)\text{ + 9(2) = 270} \\ 18(14)\text{ + 9(1) = 261} \end{gathered}[/tex]As we can see, only the time for two hours gave the lowest possible amount of what he can earn for the second equation to be correct
Hence, the minimum number of hours he must spend cleaning the table is 2 hours