First: let’s get Ben’s current age:
16+4=20
Next let’s get Dunn’s current age:
4/7=20/x
Cross multiply and divide:
x=35
Let’s now add 10 to both ages:
Ben 20+10=30
Dunn 35+10=45
Lastly, let’s find the lowest common multiple of 30 and 45 to determine the ratio:
30:45
Both 30 and 45 can be divided by 15.
30/15=2
45/15=3
Answer:
2:3