Answer:
Step-by-step explanation:
First we must find the missing number, for that we apply a simple rule of three:
3. 4
27 ------ x
x = 27 (4) / 3 = 36
Now we just do the sum:
27 + 36 = 63
(2x+2)(3x+1)
2x*3x+2x*1+2*3x+2*1
6x^2+2x+6x+2
6x^2+8x+2
Hope this helped
multiply 40 by 3/4
40 x 3/4 = 40*3 = 120, 120/4 = 30
he answered 30 correctly
40-30 = 10, he missed 10
Use substitution and substitute y into the other equation. One of the equations already gives you y in terms of x, so use that and substitute it into the other equation. y = 3x - 4
Plug into the other equation: -3y = -9x + 12
-3(3x-4) = -9x + 12
-9x + 12 = -9x + 12
This is an identity. So that means that any value of x makes this equation true. So B.
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.

