A chemist at a university needs to mix a 25% ethanol solution with a 40%ethanol solution to obtain 120mL of a 30% ethanol solution. How much of each kind is needed?
okay yeah, the two equations i got out of this was
.25a+.40b=120--->25a+40b=12000
a+b=120(.30)---->a+b=36
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yeah? no objections??? okay.......
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yeah so i times the bottom equation by (-25) and that cancelled out the A's so i was left with
15b=11100
so i divided that out and got B=740...
i plugged that into the original equation and got A=(-704)
(-704)mL of 25% ethanol solution and 740 mL of 40% ethanol solution...
THAT CANT BE RIGHT! A NEGATIVE AMOUNT OF SOLUTION?
can someone please please please help me figure out what i did wrong?