First we'll substitute
with 

Then we can separate this.

Then we'll solve this.



Then we'll plug in to find the extraneous solutions (if any)

Let us assume the number to be = x
Then
(80/100) * x = 56
4x/5 = 56
4x = 56 * 5
4x = 280
x = 280/4
= 70
The value of the unknown number is 70. I hope the procedure is clear enough for you to understand. You can always use this method for solving similar problems in future without requiring any help from outside. Only thing that needs to be taken care of is the calculation part.
Answer:
B
Step-by-step explanation:
Answer:
68 plants.
Step-by-step explanation:
Let x represent the number of plants that Reuben bought from the nursery.
We have been given that Reuben bought a whole bunch of plants at the nursery the other day. Right away, five died. So number of plant left would be
.
We are also told that then our dog dug up 2/9 of them. So number of plants left after dug-up would be
.
Further a rabbit came and ate ½ of what was left. So number of plants left would be
.
Since Reuben had only 7 plants left, so we will equate our expression with 7 and solve for x as:





Therefore, Reuben bought 68 plants at the nursery.
The pyramid formula:

The volume in this case would be:
1/3×7.9×4
=79/30×4
=10.5333...
≈10.5 m^3