Answer:
5 L of water should be added
Step-by-step explanation:
Let x L is the amount of water needed to be added.
40% sugar syrup:
Amount of syrup = 15 L
Amount of sugar [tex]=15\cdot 0.4=6[/tex] L
30% sugar syrup:
Amount of syrup = 15 + x L
Amount of sugar [tex]=(15+x)\cdot 0.3[/tex] L
Amounts of sugar are the same (we didn't add sugar, only water), then
[tex]0.3(15+x)=6\\ \\3(15+x)=60\\ \\45+3x=60\\ \\3x=60-45\\ \\3x=15\\ \\x=5\ L[/tex]
