My diary game of the 7/4/2022

Problem to find the principal amount p.in Sam cases ,the principal amount is not given but we may be given the interest amount (I)and amount paid or received A
The principal amount difination and furmuula
An lessons transcrip

The principal does not include the amount paid
P=i which is principal =interest
Example what sume of money will amount to1380in in three years at 5%p.a
Simply interest ?this is how i used math some time in my business to calculate and understand the difference I am making

(A=p+i)a=sum of amount paid or ricived
I=p×i×n
Interest amount paid and received
Sulution
P=1 a =1380n=3 i=5% =0.05p=?
=1380=p+[px0.05×3]
=1380=p+[p×0.15]

1,15
=1380=p+0.15p
1380=1.15p=p=1380
P=1200
Thanks you all for going through my normal math