Answer:
i think its the last one
Step-by-step explanation:
as 15 - 3 is 12 and then the 7
hope this helps
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Answer:
We must add 400 ml of water.
Step-by-step explanation:
We can use the following equation:

Where:
- C(i) is the initial concentration of the solution (80%)
- C(f) is the final concentration of the solution (30%)
- V(i) is the initial volume (150 ml)
- V(f) is the final volume
Now, we just need to solve the equation for V(f).



Therefore, we must add 400 ml of water.
I hope it helps you!
Answer:
25 girls
Step-by-step explanation:
Let
x denote number of boys
and
y denote number of girls
According to the statement that total 45 people came,
x+y = 45 => Eqn 1
And total paid amount was 175
So,
5x + 3y = 175 => Eqn 2
For solving, We will use the substitution method
So, from eqn 1
x = 45-y
Putting value of x in eqn 2
5(45-y) +3y = 175
225 - 5y + 3y = 175
-2y+225 = 175
-2y = 175-225
-2y = -50
2y = 50
y = 25
Putting y =25 in eqn 1
x+25 = 45
x = 45 - 25
x = 20
As y= 25
So, 25 girls came to the dance ..