Question

a drugist has two solutions of alcohol. one is 25% alcohol. the other is 45% alcohol. he wants to mix these two solutions to get 36 ounces that will be 30% alcohol. how many ounces of each of these two solutions should he mix together?

Answer 1

Set up two equations
A) x + y = 36
B) .25x + .45y = (.30 * 36)

Then solve for x and y

Answer 2

Do you know how to solve for x and y?

Answer 3

not really, are you supposed to multiply .25 to the first equation?

Answer 4

That would be one way but I would multiply equation "B" by minus 4

Answer 5

where did the minus 4 come from?

Answer 6

We'd want to have it so that one of the unknowns could be eliminated.
Multiplying equation "B" by -4 would make it
B) -x -1.8Y = -43.20
When we add that to equation "A" the "x" term gets eliminated

Answer 7

Do you want to see how that's done?

Answer 8

yes please

Answer 9

A) x + y = 36
B) -x -1.8 y = -43.20

Adding both equations we get
-.80y = -7.2

Answer 10

ohhh I see I kept multiplying the minus 4 to the a equation as well

Answer 11

so y would turn out to equal 9?

Answer 12

No you multiply equation B) .25x + .45y = (.30 * 36)
by -4 and it becomes
B) -x -1.8 y = -43.20
THen add it to equationA

And yes "y" is nine!!!

Answer 13

and so to get x would you just do 36-9?

Answer 14

which is 27 but is that how id have to solve x?

Answer 15

That is exactly how it is done

Answer 16

So basically you need 27 ounces of 25%
and 9 ounces of 45%

Answer 17

ok thank you so so much for helping me out! <3 :D

Answer 18

u r welcome