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1 Sophie's favorite (positive) number is a two-digit number. If she reverses the digits, the result is  less than her favorite number. Also, one digit is  less than double the other digit. What is Sophie's favorite number?

 

2 Seven years ago, Grogg's dad was 9  times as old as Grogg. Four years ago, Grogg's dad was 5 times as old as Grogg. How old is Grogg's dad currently?

 Jun 26, 2024
 #1
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1.   Some possibilites are

        98 , 89

        97,  79

        96,  69....etc.

 

2. 

 

D = Dad's age now     G = Grogg's age now

 

 D - 7  = 9( G - 7)   →   D - 7  = 9G - 63  →  9G - D  = 56     (1)

 

      D - 4 = 5(G - 4)  →   D - 4 = 5G -20  → 5G - D  =  16    (2)

 

Multiply (1) by 5   and (2)  by -9

 

45G - 5D = 280

-45G + 9D = -144      add these

 

4D  = 136

 

D = 136 / 4  =   34

 

cool cool cool

 Jun 26, 2024

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