Solution:
We are given:
Number of male fishes surveyed by Elena in a river = 350
Number of male fishes with eggs growing inside them = 150
Therefore the number of male fishes without eggs = 350 - 150 = 200
Now the ratio of male fish with egg cells to male fish without egg cells in the river is:

Therefore, the ratio of male fish with egg cells to male fish without egg cells in the river is 
Answer:
Amount to spend = $18.50
Purchased banana =$1.50
Apple Juice =$1.55
Gasoline $2.35
$1.50 + $1.55 = $3.05
18.50 - 3.05 = 15.45
1 Gallon of Gasoline = 2.35
Therefore,
2.35 x 6 = 14.1
15.35 - 14.1 = 1.25
To avoid exceeding budget, he can only buy
6 gallons of gasoline