For continuously compounded interest:
Amount = Principle * e^(rate * time)
A rate of 8% converted to a decimal value: r=0.08
With time t=4
and amount 1190
Plug all these values in,
1190 = Principle * e^(0.08 * 4)
And use your calculator to solve for the principle.
Maybe we'll call it P to make things easier.
1190 = P * e^(0.08 * 4)
1190 = P * 1.377
The principle is being multiplied by this 1.377,
divide by 1.377 to undo the multiplication.
864.11735 = P