Very nice, zacismyname !!! ....you're correct.....this is a good one !!!
We could also do it with one varable from the start :
Let Charlotte's age be x and Emily's age be 2x
So we have
(2x - 4)(x - 4) = 30
2x^2 - 12x + 16 = 30
2x^2 - 12x - 14 = 0
x^2 - 6x - 7 = 0
(x - 7) (x + 1) = 0 so x = 7 or x = -1 .....reject - 1 .....
So.....x = 7 = Charlotte's age and 2(7) = 14 = Emily's age
Just as you found !!!!
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