pranab01 wrote:

In a group of 100 homeowners, x homeowners had an alarm security system and y homeowners had deadbolt locks. If z homeowners had neither an alarm security system nor deadbolt locks, how many homeowners had both an alarm security system and deadbolt locks?

a) 100 – x – y – z

b) 100 – x – y + z

c) x – y – z + 100

d) x + y + z + 100

e) x + y + z – 100

We can create the equation:

Total = alarm + deadbolt - both + neither

100 = x + y - both + z

both = x + y + z - 100

Answer: E

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