Answer:
c. 120 units^3
Step-by-step explanation:
L x W x H = <em>V</em>
3 x 4 / 2 = 6
6 x 20 = 120
I'm thinking this is what the problem looks like:

. The first thing to do is to move the

over to the other side because it has a common denominator with the other side. Doing that and at the same time combining them over their common denominator looks like this:

. The best way to solve for x now is to cross-multiply to get 3(4-x)=-4(x-4). Distributing through the parenthesis is 12 - 3x = -4x + 16. Solving for x gives us x = 4. Of course when we sub a 4 back in for x we get real problems, don't we? Dividing by zero breaks every rule in math that there ever was! So, yes, the solution is extraneous.
Answer:
133.33g
Step-by-step explanation:
Let the:
Mass of 1.2g/cm³ of liquid = x
Mass of 1.8g/cm³ of liquid = y
From our Question above, our system of equations is given as:
x + y = 400........ Equation 1
x = 400 - y
1.2 × x + 1.8 × y = 1.6 × 400
1.2x + 1.8y = 640..... Equation 2
We substitute, 400 - y for x in Equation 2
1.2(400 - y) + 1.8y = 640
480 - 1.2y + 1.8y = 640
- 1.2y + 1.8y = 640 - 480
0.6y = 160
y = 160/0.6y
y = 266.67 g
Solving for x
x = 400 - y
x = 400 - 266.67g
x = 133.33g
Therefore, the mass of the liquid of density 1.2g/cm³ is 133.33g