Answer:
39 dimes
Explanation:
From the graph:
• Total number of nickels = 9+4+7=20
,
• Total number of dimes = 7+10+9 = 26
The ratio of total nickels to total dimes = 20:26
If the total number of nickels the students donate is increased to 30, we have:
[tex]\frac{\text{Total Nickels}}{\text{Total Dime}}\colon\frac{20}{26}=\frac{30}{x}[/tex]
We then solve for x:
[tex]\begin{gathered} 20x=30\times26 \\ x=\frac{30\times26}{20} \\ x=39 \end{gathered}[/tex]
The number of dimes they should donate to keep the ratio of total nickels to total dimes the same is 39.