Problema Solution
Demi multiples a number by 2 and then adds her starting number to the product. Kylie adds this same original number to itself and then multiples that sum by 2. The difference between Demi's and Kylie's results is 9. What is their starting number?
Answer provided by our tutors
let x = the starting number
Demi multiples a number by 2 and then adds her starting number to the product
2x + x
Kylie adds this same original number to itself and then multiples that sum by 2
(x + x)2
The difference between Demi's and Kylie's results is 9
(2x + x) - (x + x)2 = 9
by solving we find
x = -9
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the starting number is -9.