Calculate how much 1 salt solution must be mixed with how mu

Calculate how much 1% salt solution must be mixed with how much 5% salt solution to make 100 milliliters of 2% salt solution. You\'ll need ____ milliliters of the 5% salt solution. Type in your numerical answer only; do not type any words or letters with your answer.

Solution

x L of 1% salt
y L of 5% salt

x + y = 100

Now, equating salt content :
0.01x + 0.05y = 0.02*100
0.01x + 0.05y = 2

Multiply that by 100 :
x + 5y = 200
x + y = 100

Solving :
y = 25 and x = 75

So,
75 mL of 1%
25 mL of 5%