SOLUTION: Aida is now nine-fifths as old as he was 20 years ago. How old is he now?

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Question 673174: Aida is now nine-fifths as old as he was 20 years ago. How old is he now?
Answer by rm29924(97) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = Aida's age now
Aida's age 20 years ago = x-20
Aida is now nine-fifths as old as he was 20 years ago.
so we multiply his age 20 years ago by 9/5
9/5(x-20)
the solution to that is his age now
so our equation is
9/5(x-20)=x
to get rid of the fraction multiply both sides by 5
45/5(5x-100)=5x
9(5x-100)=5x
45x-900=5x
add 900 to both sides
45x=5x+900
subtract 5x from both sides
40x=900
divide 40 from both sides
x=22.5
answer: Aida is 22 1/2 years old
check answer:
9/5(x-20)=x
9/5(22.5-20)=22.5
9/5(2.5)=22.5
multiply both sides by 5 to get rid of the fraction
9(12.5)=112.5
112.5=112.5