Vertices Problem

from Rob Southern

 

System of Equations Puzzle

from: Matematik Dünyası

 

Equation to Solve in Your Head!

 (from Boris Kordemsky - The Moscow Puzzles)

Problem 106: Height of the table

Problem 46: Feet and Tails

Mrs. Eleanor Abernathy has 7 female cats. This May all her cats gave birth to new kittens. Some of the cats had 3 babies, some had 4 and the remaining ones had 5 baby cats. 

The number of cats that gave birth to 5 babies is 1 less than the number of cats that have quadruplets or triplets.

Mrs. Abernathy is interested in counting and she counts 150 legs in her house. 

Can you find the number of cats who has quints(5 babies)?