SOLUTION: Please help me solve the follow two problems!! 1/x-a=1/b, find x. and An apartment building contains 12 units consisting of one- and two-bedroom apartments that rent for

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Question 284891: Please help me solve the follow two problems!!
1/x-a=1/b, find x.
and
An apartment building contains 12 units consisting of one- and two-bedroom apartments that rent for $360 and $450 per month, respectively. When all units are rented, the total monthly rental is $4,950. What is the number of two-bedroom apartments?
Thank you.
Answer by CubeyThePenguin(3113) About Me  (Show Source):
You can put this solution on YOUR website!
1/x - a = 1/b
1/x = 1/b + a = (ab + 1)/b
x = b%2F%28ab%2B1%29
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a = number of 1 bedroom apartments
b = number of 2 bedroom apartments

a + b = 12
360a + 450b = 4950

Multiply the first equation by 450.

450a + 450b = 5400
360a + 450b = 4950

Subtract to get 90a = 450, so a = 5.

There were 5 one-bedroom apartments and 7 two-bedroom apartments.