Question 579924
In 10 years time Bill will be 30 years old.
 John will then be half of Bill's age.
 How old is John now? 
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I'm not sure what "picture form" is but we can do it this way.
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let j = John's present age
Let b = Bill's present age
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Write an equation for each statement:
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"In 10 years time Bill will be 30 years old."
(b + 10) = 30
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"John will then be half of Bill's age."
j + 10 = .5(b+10)
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From the 1st equation we can replace (b+10) with 30
j + 10 = .5(30)
j + 10 = 15 
j = 15 -10
j = 5 yrs is John's present age