12. algebra there are 92 students in the third and fourth grades at johnsonville elementary. of these, 47 are in fourth grade. write an equation to find how many third graders there are. use a question mark to represent the unknown number and solve.

The number of students in third grade 45

Step-by-step explanation:

Given : There are 92 students in the third and fourth grades at Johnsonville Elementary.

Of these, 47 are in fourth grade.

To Find : Write an equation to find how many third graders there are. Use a question mark to represent the unknown number and solve.

Solution:

Number of students in fourth grade = 47

Let ? be the number of students in third grade

So, total number of students =

We are given that There are 92 students in the third and fourth grades

So,

Hence  an equation to find how many third graders there are is   and the number of students in third grade is 45.

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.