In a group of Houses,40 had dogs,30 had cats and 10 houses having both dogs and cats. what is the number of houses?
Choices
A) 30 B) 60 C) 40 D) 45 E) 50

Rationale: make a venn diagram , and enter your data . let the number of houses be x 30 + 10 + 20 = x x = 60 so number of houses were = 60 answer b
Answer: B