Answer:
[tex]23.1\%[/tex]
Step-by-step explanation:
Stefanie's mixture of 18 grams has a 20% sugar content. Therefore, there are grams of sugar in her syrup.
John's mixture of 30 grams has a 25% sugar content. Therefore, there are grams of sugar in her syrup.
Therefore, if they mix their syrups together, there will be 11.1 grams of sugar and 48 total grams of content.
The concentration of sugar in the new mixture is [tex]\frac{11.1}{48}=\fbox{$23.1\%$}[/tex](rounded to one decimal place).
