ANSWER
Marty filled 8 buckets of water
Step-by-step explanation
Let
• x: number of buckets Marty filled
,
• y: number of buckets Debby filled
,
• z: number of buckets Melissa filled
We know that Debby filled 10 times as many buckets as Marty:
![y=10x](https://img.qammunity.org/2023/formulas/mathematics/college/1ffexhlgy1m3olovbakngawpa38j9k06hv.png)
And that Melissa filled 6 times as many buckets as Marty:
![z=6x](https://img.qammunity.org/2023/formulas/mathematics/college/vmd2r1zadvaozsw1gqpak6ku6n2w50a6r8.png)
All three of them together fulled 136 buckets:
![x+y+z=136](https://img.qammunity.org/2023/formulas/mathematics/college/mtxepsgq869ifr1ld6f71jx3q23ghvls18.png)
Replace y and z as functions of x:
![x+10x+6x=136](https://img.qammunity.org/2023/formulas/mathematics/college/lsx7cksa23fh338n9kjwvsf007otgvwiel.png)
And solve for x. First add like terms:
![\begin{gathered} (1+10+6)x=136 \\ 17x=136 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/9d94c0xgstgwwjtti8vgiy9c6njxqjuwad.png)
And divide both sides by 17:
![\begin{gathered} (17x)/(17)=(136)/(17) \\ x=8 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/5it1vyo10u7zx74picxbx3hobj3chmdbqk.png)
We found that Marty filled 8 buckets of water.