Answer: [tex]\frac{1}{4}[/tex] is used by Manny and Susan both used for their project.
Step-by-step explanation:
Suppose that Number of eggs in a carton = 100
Number of eggs that Manny uses = 13
Number of eggs that Susan uses = 12
Total number of eggs both of them uses is given by
[tex]12+13=25[/tex]
So, fraction of the eggs that Manny and Susan use for their project is given by
[tex]\frac{25}{100}=\frac{1}{4}[/tex]
Hence, [tex]\frac{1}{4}[/tex] is used by Manny and Susan both used for their project.