# Math

#### Mmm1234

##### New member
A chemist needs 30 liters Of 25% acid solution.
she has containers of 10% solution and 30% solution. How many liters of each should she combine to get the needed solution? If necessary express your answer in decimals and round to the nearest tenth.

#### Subhotosh Khan

##### Super Moderator
Staff member
A chemist needs 30 liters Of 25% acid solution.
she has containers of 10% solution and 30% solution. How many liters of each should she combine to get the needed solution? If necessary express your answer in decimals and round to the nearest tenth.
If I were to do this problem. I would fist define unknowns:

Volume of 20% solution needed = W liters

Volume of 30% solution needed = H liters

Then I will start working with volume of alcohol present in different solutions.

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:

#### tkhunny

##### Moderator
Staff member
A chemist needs 30 liters Of 25% acid solution.
she has containers of 10% solution and 30% solution. How many liters of each should she combine to get the needed solution? If necessary express your answer in decimals and round to the nearest tenth.
Equate Something. Seriously, that's all that is required.

A few definitions: <== Feel free to WRITE DOWN your definitions. MUCH easier to keep track of everything.

Measurements are in liters.
30 = Amount of Total 25% Solution
x = Amount of 10% Solution
(30-x) = Amount of 30% Solution

Equate Acid:

x * 0.10 + (30-x) * 0.30 = 30 * 0.25

Equate Non-Acid:

x * 0.90 + (30-x) * 0.70 = 30 * 0.75

At times, one or the other will look easier. Go with that. No need to memorize just one way to proceed and wind up doing it the hardest way possible about half the time.