Question

5 of the people on John's street know how to roller skate. 8 people know how to swim, and 3 people know both how to roller skate and how to swim. How many people know how to roller skate or how to swim or both?

Answer 1

Explanation:

`n(aub) = n(a) + n(b) - n(anb) \\ = 8 + 5 - 3 \\ = 8 + 2 \\ = 10 \\ thank \: you`

Answer 2

• A=people know how to roller skate
• B =People know to swim
• A intersection B=People know both
• A union B=total people

`\\ \sf\longmapsto n(A\cup B)=n(A)+n(B)-n(A\cap B)`

`\\ \sf\longmapsto 5+8-3`

`\\ \sf\longmapsto 13-8`

`\\ \sf\longmapsto 10`