SOLUTION: Matthew is 3 times as old as Jenny. In 7 years, he will be twice as old as she will be then. How old is each now?
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-> SOLUTION: Matthew is 3 times as old as Jenny. In 7 years, he will be twice as old as she will be then. How old is each now?
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You can put this solution on YOUR website! Matthew is 3 times as old as Jenny. In 7 years, he will be twice as old as she
will be then. How old is each now?
:
Let M = Matthew's age now
Let J = Jenny's age now
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Their ages in 7 years:
(M+7) and (J+7)
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Write an equation for each statement:
;
"Matthew is 3 times as old as Jenny."
M = 3J
:
In 7 years, he will be twice as old as she will be then."
(M+7) = 2(J+7)
Simplify equation
M + 7 = 2J + 14
M = 2J + 14 - 7
M = 2J + 7
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How old is each now?
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From the 1st equation; substitute 3J for M in the above equation
3J = 2J + 7
3J - 2J = 7
J = 7 yrs is Jenny's age now
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Then from the 1st equation:
M = 3(7)
M = 21 yrs is Matthew's age now
;
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Check solution in the statement:
"In 7 years, he will be twice as old as she will be then."
21 + 7 = 2(7+7)
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