Hello here is a solution :
<span> midpoint between A and B,is :C( (Xa+xb)/2; (ya+yb)/2)
C( (-1-3)/2;(5-7)/2)
C(-2 ; -1)</span>
as we move down the list as we push the *digits* to the *left*through the decimal *point* *each* *number has been 10*. and so we can easily *multiply* or divide by *a* power of *10* because of our system of positional numeration. Each Place belongs to the next power of *10*.
