+52 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?
+129643 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
