Amount of 15% solution = 10 litres
Amount of 45% solution = 20 litres
This is based on simultaneous equations.
Let x represent the amount of the 15% solution.
Let y represent the amount of the 45% solution. Thus;
0.15x + 0.45y = 0.35(x + y) - - - (eq 1)
Since they both combine to make 30 litres solution, then;
x + y = 30 - - - (eq 2)
From eq(2), let's make x the subject to get; x = 30 - y
Putting 30 - y for x in eq 1 gives;
0.15(30 - y) + 0.45y = 0.35(30 - y + y)
4.5 - 0.15y + 0.45y = 10.5
Rearranging gives;
0.3y = 6
y = 6/0.3
y = 20 litres
Putting 20 for y in eq 2 gives;
x + 20 = 30
x = 30 - 20
x = 10 litres
Read more at; brainly.com/question/10185505
