Which subject in the problem is represented by x?

Question

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 twice the number of turtles. In total, he counted 54 turtles and crayfish. How many frogs were there? 

Which subject in the problem is represented by x?

Frogs = ___

Answer 1

We can give a different letter to each animal

T for turtles

F for frogs

C for crayfish

He counted 4 more frogs than turtles, so

F = T + 4

Crayfish are 3 more than twice the number of turtles, so

C = 2T + 3

In total he counted 54 turtles and crayfish, so

T + C = 54 but remember that C = 2T + 3 so we can substitute

T + 2T+3 = 54 so now we can put like terms together T + 2T and we have

3T + 3 = 54 now we can use basic algebra to solve for T. First subtract 3 on both sides.

3T = 51 Next you can divide both sides by 3.

T = 17 This is the number of turtles.

Since there is a T in every other equation, Turtles are the X you are looking for.