Question 1105351
Give some variables to initial quantity each had.
x, how much Justina had
y, how much Frederick had



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If Frederick and justina spent $8 & $16 respectively, justina would still have $70.
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The means that {{{x-16=70}}}.  That's all you can do so far.



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If Frederick and justina spent $16 & $8 respectively, justina would have $430 left
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This part means  {{{x-8=430}}}.


The description has enough information only for two equations in the variables, x.  NO value for x will satisfy both equations, and not enough information to solve for y.