In a chemical equation, what are the formulas to the left of the arrow called?

A chemical equation consists of the chemical formulas of the reactants (on the left) and the products (on the right). The two are separated by an arrow symbol (“→” usually read aloud as “yields”). Each individual substance's chemical formula is separated from others by a plus sign.

Step-by-step explanation:

Let us assume the initial number of bacteria in the culture = x

After 1 hour,

The number of bacteria = 185x/100

                                     = 1.85x

After 2 hours,

The number of bacteria = (185 * 1.85x)/100 

                                     = 3.42x

So

3.42x = 12500

x = 12500/3.42

  = 3654.97

  = 3655

From the above deduction, we can conclude that the initial number of bacteria in the culture is 3655