The amount of algae covering the smith's backyard pond doubled every day until it was completely covered in algae on day 30 of the month. on what day of that month was 75% of the pond algae-free?

To solve this problem, work backwards.

On day 30, it is 100% algae.

On day 29, it is 50% algae.

On day 28, it is 25% algae(or 75% algae free).  

It was on Day 28.

5=812a+9+3

step 1: simplify both sides of the equation.

5=812a+9+3

5=(812a)+(9+3)(combine like terms)

5=812a+12

5=812a+12

step 2: flip the equation.

812a+12=5

step 3: subtract 12 from both sides.

812a+12−12=5−12

812a=−7

step 4: divide both sides by 812.

812a /812 = -7/812

a= -1/116

so the answer is

a=   -1/116

f . i can go whenever i feel like it bc it is confidential meaning only i would know how much i deposited besides the bank and they wouldnt care bc when you make a deposit you are using their services which means they are using there competition and gaining more customers

and if they dont well then thats less customers for them in a less profitable way

plz mark brainliest