Answer:the number of kids that used the public pool that day is 122
the number of adults that used the public pool that day is 92
Step-by-step explanation:
Let x represent the number of kids that used the public pool that day.
Let y represent the number of adults that used the public pool that day.
214 people used a public swimming pool. This means that
x + y = 214
1.50 for kids and $2.25 for adults. The receipt totaled to $390. This means that
1.5x + 2.25y = 390 - - - - - - - - - -1
Substituting x = 214 - y into equation 1, it becomes
1.5x
1.5(214 - y) + 2.25y = 390
321 - 1.5y + 2.25y = 390
- 1.5y + 2.25y = 390 - 321
0.75y = 69
y = 69/0.75 = 92
Substituting y = 92 into x = 214 - y, it becomes
x = 214 - 92 = 122
So,
We have three placeholders.
x, y, and z will represent the number of cookie boxes they sold for the first, second, and third weeks, respectively.
"The girls sold 5 more boxes the second week than they did the first."
x + 5 = y
"They doubled the sales of the second week for the third week."
z = 2y
"To sell a total of 431 boxes of cookies"
x + y + z = 431
Now we have our three equations.
x + 5 = y
z = 2y
x + y + z = 431
Obviously, we can substitute y and z in the last equation, because the other two open sentences tell us what they are.
x + (x + 5) + 2(x + 5) = 431
x + x + 5 + 2(x + 5) = 431
Collect Like Terms.
2x + 5 + 2(x + 5) = 431
Distribute.
2x + 5 + 2x + 10 = 431
Collect Like Terms.
4x + 15 = 431
Subtract 15 from both sides.
4x = 416
Divide both sides by 4.
x = 104
Now we can use the other two original sentences to figure out what y and z are.
x + 5 = y
104 + 5 = y
109 = y
z = 2y
z = 2(109)
z = 218
Now, to check, add x, y, and z.
x + y + z = 431
104 + 109 + 218 = 431
213 + 218 = 431
431 = 431 This checks.
The Girl Scouts sold 104 cookie boxes on the first week, 109 boxes on the second week, and 218 boxes on the third week.
Answer:

Step-by-step explanation:
Given: Equation is 
To find: flaw in Gwendolyn's work and the correct solution to the equation.
Solution:
In the given question,
the first step is 
The second step is 
(This step is obtained on multiplying
by
)
The third step is 
This step is wrong as on transposing 12 from left side of the equation in the second step to the right side, the following equation is obtained:

So, the correct solution is 
Answer: x=40
Step-by-step explanation x-0.3x=28
Add similar elements x-0.3x=0.7x
0.7x=28
Multiply both sides by 10
0.7x · 10= 28 · 10
Refine
7x=280
Divide both sides by 7
Simplify
x = 40