Answer:
55
Step-by-step explanation:
We can use the given relations to write an equation that can be solved for my age 25 years from now.
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Let x represent my age in 25 years. The age relationships can be summarized as ...
- in 25 years -- me: x
- now -- me: x-25; dad: 3(x-25) = 3x-75
- 10 years ago -- me: x-35; dad: 3x -85
We know 10 years ago my dad was 4 times my age, so we have ...
4(x -35) = 3x -85
4x -140 = 3x -85 . . . eliminate parentheses
x = 55 . . . . . . . . . . . add 140-3x
I will be 55 in 25 years from now.
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Additional comment
10 years ago, I was 20 and my dad was 80. Now, I'm 30 and my dad is 90. In 25 years, I'll be 55.
