Solution: suppose there are x turtles.

Since there are 40 turtles and cranes, there are (40-x) cranes.

According to the meaning of the question, the equation can be listed as,

4*x+2*(40-x)= 1 12

Resolved, 2x=32

x= 16

Then (40-x)=40- 16=24.

That is 16 turtles and 24 cranes.

Extended data:

1, the properties of the equation

Adding (or subtracting) the same number or the same algebraic expression on both sides of the (1) equation at the same time, the result is still an equation.

(2) Both sides of the equation are multiplied or divided by the same number that is not 0 at the same time, and the result is still an equation.

(3) Transitivity of the equation. If a=b and b=c, then a = c.

2, the solution of a linear equation

(1) General method

There are five steps to solve a linear equation with one variable, namely, denominating, removing brackets, shifting terms, merging similar terms, and the transformation coefficient is 1.

For example: (x+3)/6=(x+7)/ 10.

Solution: 10*(x+3)=6(x+7)

10x+30=6x+42

10x-6x=42-30

4x= 12

x=3

(2) the root formula method

For the unary linear equation ax+b=0(a≠0), the root formula is X =-B/A.

Example: if 3x- 14=0, then x=-b/a= 14/3.

Baidu encyclopedia-unary linear equation