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

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

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

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

$\\ \sf\longmapsto 13-8$

$\\ \sf\longmapsto 10$

Answer 2

Step-by-step explanation:

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