A chemist wishes to make 3 liters of a 7% acid solution by mixing a 9% acid solution and a 4% acid solution. Let x represent the number of liters of the 9% acid solution. Write an equation to solve for x.

Question

hulagirlmb · Answer

I only have 15 minutes before it's due! Please help

anonymous · Answer

ok lets work quick

hulagirlmb · Answer

I'll post the answer choices in a drawing one second

anonymous · Answer

$x$ is the number of liters of 9%k solution,  making the number of liters of 4%  solutions $3-x$ 
solve 
$$.09x+.04(3-x)=.07\times 3$$

hulagirlmb · Answer

Thank you

anonymous · Answer

or better still, solve 
$$9x+4(3-x)=7\times 3$$

hulagirlmb · Answer

Ok one sec

anonymous · Answer

$$9x+12-4x=21\
5x+12=21\
5x=9\
x=\frac{9}{5}=1.8$$

hulagirlmb · Answer

I got x=1.8

hulagirlmb · Answer

Ok good

anonymous · Answer

yay

hulagirlmb · Answer

Thank you so much, I have to get a good grade on this XD

anonymous · Answer

good luck
that all or you got more?

hulagirlmb · Answer

I already submitted, somebody else helped me on 2 of the problems and we didn't get them right. But thank you so much for helping me on those 2 because I really didn't understand that type of problem

anonymous · Answer

i don't think i skipped any steps, you can look back and see if they are clear 
and ask if they are not
this 'mixture" problems are usually confusing at first

hulagirlmb · Answer

Ok thank you

perl · Answer

nice work