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# help

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I need to use algebra

Seven years ago, Grogg's dad was 6 times as old as Grogg, and 4 years ago, his dad was 4 times as old as Grogg. How old is Grogg's dad currently?

May 7, 2023

#1
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it would be 6x4+4 and see what that gives you.

May 7, 2023
#2
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I think 6x4+4 gives you an F in math.

Seven years ago, Grogg's dad was 6 times as old as Grogg, and 4 years ago, his dad was 4 times as old as Grogg. How old is Grogg's dad currently?

Call Grogg's age now "G" and his dad's age now "D"

Seven years ago                           (D – 7)  =  6 * (G – 7)

Four years ago                              (D – 4)  =  4 * (G – 4)

Multiply them out                            D – 7  =  6G – 42          (eq 1)

D – 4  =  4G – 16          (eq 2)

Subtract (eq 2) from (eq 2)                – 3  =  2G – 26

23  =  2G

G  =  11.5

Find D by

plugging G back into (eq 1)             D – 7  =  (6)(11.5) – 42

D – 7  =  69 – 42

D  =  27 + 7

D  =  34

plugging G back into (eq 2)              D – 4  =  (4)(11.5) – 16

D – 4  =  46 – 16

D  =  30 + 4

D  =  34

.

Guest May 8, 2023
#3
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typo

Subtract (eq 2) from (eq 2)  should have been  Subtract (eq 2) from (eq 1)

Guest May 9, 2023