Ramon was studying pond life in Doyle Park. In two hours, he counted four more frogs than turtles. The number of crayfish he counted was three more than the twice the number of turtles. In total he counted 54 turtles and crayfish. How many frogs were there?

Let us assume the number of turtles = x

Then

Number of frogs = x + 4

Number of crayfish = 2x + 3

Total number of turtles and crayfish = 54

Then we can write the equation as

x + 2x + 3 = 54

3x + 3 = 54

3x = 54 - 3

3x = 51

x = 51/3

= 17

Then

The number of frogs = x + 4

= 17 + 4

= 21

So there are 21 frogs in the pond that has been counted by Ramon.