So 2x+12=5x-9
you want all of the unknowns on one side and all of the known values on the other or
subtract 2x from both sides
12=3x-9
add 9 to both sides
21=3x
divide both sides by 3
7=x
8 litres (amount of 20% solution needed) and 7 litres for (amount of 50% solution needed)
<u>Step-by-step explanation:</u>
Let consider ‘x’ for 20% acid solution and (15 – x) for 50% acid solution. And so, the equation would be as below,
20% in x + 50% in (15 – x) = 15 litres of 34%
Convert percentage values, we get
0.20(x) + 0.50 (15 – x) = 15 (0.34)
0.20 x + 7.5 – 0.50 x = 5.1
-0.3 x + 7.5 = 5.1
0.3 x = 7.5 – 5.1
0.3 x = 2.4

Apply ‘x = 8’ value in (15 – x) we get,
15 – 8 = 7 litres
The value of 7 litres for (amount of 50% solution needed)
4x/15 = 60/x
4x^2 = 900
x^2 = 225
x = 15
Answer:
x = e^2/2 + 3
Step-by-step explanation:
Solve for x:
log(2 x - 6) = 2
Hint: | Eliminate the logarithm from the left hand side.
Cancel logarithms by taking exp of both sides:
2 x - 6 = e^2
Hint: | Isolate terms with x to the left hand side.
Add 6 to both sides:
2 x = e^2 + 6
Hint: | Solve for x.
Divide both sides by 2:
Answer: x = e^2/2 + 3