Answer:
$20
Step-by-step explanation:
We are given the percentages of how much she spent on each purchase but we need the percentage of what is left after each purchase. We calculate this by subtracting each percentage from 100% like so.
100% - 40% = 60%
100% - 20% = 80%
100% - 50% = 50%
Next we need to do is change the percentages into decimal format. We do this by moving the decimal 2 digits to the left. Therefore the percentages wasted are the following
60.0% ⇔ 0.60
80.0% ⇔ 0.80
50.0% ⇔ 0.50
Now that we have the percentages in decimal format we can calculate the total price (t) by retracing the spending process. The spending process was following.
So we have to retrace by solving for 
, then 
, and finally (t)
... divide both sides by 0.50
.... divide both sides by 0.20
.... divide both sides by 0.60
Finally we can see that the Total amount of money that Alice had before lunch was $20
1.62, 15/20, 16.2% is the answer
Answer:
The height of water in the second tank is 2ft
Step-by-step explanation:
In this question, we are asked to calculate the height of water in a second tank if the content of a first tank is poured into the second tank.
The plot twist to answering this question is that we need to note the volume of water in the first tank. Although the first tank has dimensions of 2ft by 3ft by 2ft height, the water in the tank only rose to a height of 1 feet.
Hence, to calculate the volume of the water in the first tank, the width and the length of the tank still remain the same, the only difference here is that we work with a height of 1 feet since the Water is not full.
Mathematically, the volume of water present in the tank will be;
V = l * b * h
V = 4 * 3 * 1 = 12 cubic feet
Now, this content is emptied into a second tank. Since the volume of water here is the same; this means;
12 cubic feet = 3 * 2 * h
We ignore the 4ft height as it is just the height of the tank and not the height of the water in the tank
6h = 12 cubic feet
h = 12/6 = 2 ft
