SOLUTION: One person is 3 years old. Another is 57 years old. I need to write an equation which models how old each person will be when the older person is three times as old as the younger

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Question 683682: One person is 3 years old. Another is 57 years old. I need to write an equation which models how old each person will be when the older person is three times as old as the younger person.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +y+ = the age of the younger person
Let +x+ = the age of the older person
---------------
I can put the equation into the form
+y+=+m%2Ax+%2B+b+
I can say
(1) +3+=+m%2A57+%2B+b+
I can also say
(2) +0+=+m%2A54+%2B+b+ ( older person was 54 when younger person was born )
(2) +b+=+-54m+
and
(1) +3+=+57m+-54m+
(1) +3m+=+3+
(1) +m+=+1+
and
(2) +b+=+-54m+
(2) +b+=+-54+
So, the equation is
+y+=+x+-+54+
Here's the plot
+graph%28+400%2C+400%2C+-5%2C+100%2C+-5%2C+70%2C++x+-+54+%29+