Let the number of friends that ate with Ron be represented by F. That means the total amount of people that ate that day were 1 + F
If each of them ate 4 slices, and the pizza only has 12 slices, that means there could only have been 12/4 = 3 people eating
If the total number of people eating was 3, and if was also represented by 1+F then we have 3 = 1+ F
Solving for F we have 3-1 = F
F = <<2=2>>2 friends ate with Ron
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