A chemist has three different acid solutions. The first acid solution contains 20 % acid, the second contains 40 % and the third contains 70 % . He wants to use all three solutions to obtain a mixture of 76 liters containing 50 % acid, using 2 times as much of the 70 % solution as the 40 % solution. How many liters of each solution should be used? ​

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

let x be the money she spent so that she can earn the free t-shirt.

since, she already spent $112.49

⇒

also, as per the statement: jennifer must spend $250 or more in order to qualify for a free t-shirt at the store.

then,

we have an inequality i.,e

subtract 112.49 from both sides we get;

therefore, $137. 51 more money does jennifer need to spend so that she can earn the free t-shirt

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step-by-step explanation: