For this case we have that the variable "L" represents the amount of hours that Landen spent on the beach.
So, let variable "M" be the number of hours Mateo spent on the beach. If we are told that Mateo spent 15% less hours on the beach than Landen, we make a rule of three:
L --------------> 100%
x --------------> 15%
Dode "x" represents hours equivalent to 15% less than Matthew spent on the beach.
![x = \frac {15 * L} {100}\\x = 0.15L](https://img.qammunity.org/2020/formulas/mathematics/middle-school/fhr5p9ef66azyjjps0zqkpv4m9kiq17smv.png)
Then Mateo was on the beach the following number of hours:
![M = L-0.15L\\M = 0.85L](https://img.qammunity.org/2020/formulas/mathematics/middle-school/kspp4os3310jrkfmou2du3y524mrrsssdz.png)
Answer:
![M = 0.85L](https://img.qammunity.org/2020/formulas/mathematics/middle-school/lq7dypk06k6xgkdgrk16g47ak39thzqzhd.png)