#1. 4:7 8:14 12:21
#2. 5:7 10:14 15:21
#3. 9:7 18:14 27:21
#4. 11:2 22:4 33:6
#5. 7:21 14:42 21:63
#6. 7:5 14:10 21:15
#7. Equals
#8. Equals
#9. Equals
#10 not equal
#11 not equal
# 12. Equals
#13. y=20
#14. y=14
#15. y=15
#16. y=40
#17. y=40
#18. y=36
Answer:

Step-by-step explanation:
Given 2 similar figures with ratio of sides = a : b, then
ratio of areas = a² : b²
Here ratio of sides = 52 : 68 = 13 : 17 ← in simplest form, thus
ratio of areas = 13² : 17² = 169 : 289 = 
15ft per sec would be the unit rate.