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.


Answer:
Step-by-step explanation:
you just need to add both equations
you will get 3y=12+6=18
3y=18
y=6
now replace y=6
3x+12=6
3x=6-12
3x=-6
x=-2
(-2,6)
It would be:
-.72 < -5/8 < -.6 < -7/12
Answer:
0.4

Step-by-step explanation: