For this case we have missing
of fence to be painted.
To paint
of fence we used:
gallons of paint. So, we make a rule of three:
![\frac {5} {4} ------------> \frac {5} {7}\\x --------------------------> \frac {2} {7}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/6jhku75q8szfzzsmw3t1xaf9zrdunj6vn7.png)
Where the variable "x" represents the gallons of paint needed to paint the missing fence
![x = \frac {\frac {2} {7} * \frac {5} {4}} {\frac {5} {7}}\\x = \frac {70} {140} = \frac {1} {2} = 0.5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/s6n4lzfaiuc035xh32nanhjed44fwznub5.png)
Thus, 0.5 gallons of paint is missing for the missing fence.
Answer
0.5 gallons