$A$ statement that needs a proof is called a........

Solve the following question using appropriate Euclid's axiom:
In the figure:
$BM = BN$,$M$ is the mid-point of $AB$ and $N$ is the mid-point of $BC$. Show that $AB = BC$.

Which of the following needs a proof?

State whether the following statement is True or False. Justify your answer.
If the area of a triangle equals the area of a rectangle and the area of the rectangle equals that of a square,then the area of the triangle also equals the area of the square.

The edges of a surface are ............

Solve the equation $a-15=25$ and state which axiom do you use here.