Algebra 2 word problem help, need an answer

Question

Right now Bob is n times as old as his cousin Alexandra, who is 7 years old. In two years, Bob's grandmother Jane, who is now 88 years old, will be n-1 times as old as Bob will be then. How old is Bob now?

Answer 1

 

NOW:

 

  Alexandria = 7

  Bob = 7n

  Jane = 88

 

2 YEARS FROM NOW:

  

  Jane = 88 + 2 = 90

  Bob = 7n + 2

  Jane = (n - 1)(7n + 2)

  

Since (in 2 years) Jane will be n -1 times Bob;

 

  90 = (n - 1)(7n + 2)

  90 = 7n² + 2n - 7n - 2 

  90 = 7n² - 5n - 2

   0  = 7n² - 5n - 92

   0 = (7n + 23)(n - 4)

   

   7n + 23 = 0; 7n = -23 ... discard ... age cannot be negative

 

   n - 4 = 0

   n = 4

 

Bob is 7n = 7(4) = 28

 

Bob is 28 years old.