Answer:
The number of liters of 25% acid solution = x = 160 liters
The number of liters of 40% acid solution = y = 80 liters
Step-by-step explanation:
Let us represent:
The number of liters of 25% acid solution = x
The number of liters of 40% acid solution = y
Our system of Equations =
x + y = 240 liters....... Equation 1
x = 240 - y
A 25% acid solution must be added to a 40% solution to get 240 liters of 30% acid solution.
25% × x + 40% × y = 240 liters × 30%
0.25x+ 0.4y = 72...... Equation 2
We substitute 240 - y for x in Equation 2
0.25(240 - y)+ 0.4y = 72
60 - 0.25y + 0.4y = 72
Collect like terms
- 0.25y + 0.4y = 72 - 60
0.15y = 12
y = 12/0.15
y = 80 Liters
Solving for x
x = 240 - y
x = 240 liters - 80 Liters
x = 160 liters
Therefore,
The number of liters of 25% acid solution = x = 160 liters
The number of liters of 40% acid solution = y = 80 liters
You have to be very careful how you set this up. For every girl (who counts as 1) there are 3 boys (who count as 3). The total number in the proportion is 3 + 1 =4. You are given a total, but that is both boys and girls. That's why you need the 4.
3/4 = x / 236 Cross multiply
4x = 3 * 236
4x = 708 Divide by 4
x = 708/4
x = 177
There are 177 boys at the school and 236 - 177 = 59 girls.
Answer:
0.268
Step-by-step explanation:
In the attached file
Answer:
#5: d=22, #6: 
, #7: 
Step-by-step explanation:
#5:
#6:
#7:
It is a trick question 13+13 DOES equal 26
