The answer is C.
This is because 7 must be greater than 12-g.
G cannot equal 5 and below because 12-5=7.
Therefore C is the only answer that works.
Variables - a quantity that may change, depends on the context of the math problem. Ex: x,y
Terms - a variable, or constant, that is multiplied by a variable or variables.
Ex: 5x + 2 + 3y <-- has 3 terms
Coefficient - the constant that multiplies the variable and is next to a variable, Ex: (5x) <-- coefficient is 5
Constants - A fixed value such as 5, 6, 7, etc
Answer:
First brand of antifreeze: 21 gallons
Second brand of antifreeze: 9 gallons
Step-by-step explanation:
Let's call A the amount of first brand of antifreeze. 20% pure antifreeze
Let's call B the amount of second brand of antifreeze. 70% pure antifreeze
The resulting mixture should have 35% pure antifreeze, and 30 gallons.
Then we know that the total amount of mixture will be:

Then the total amount of pure antifreeze in the mixture will be:


Then we have two equations and two unknowns so we solve the system of equations. Multiply the first equation by -0.7 and add it to the second equation:



+

--------------------------------------



We substitute the value of A into one of the two equations and solve for B.


1.4/7 in simplest form is 0.2/1 because you divide each side by 7.
The answer is 3. 3 is the answer.