This is basically a division equation. Solve the top and the bottom, then divide. The numerator (top part) is 3.95 multiplied by 10 to the second power, which is the same as 3.95 times 100, which is the same as 395.
The denominator is 1.5 times 10 to the 6th power, which is the same as 1.5 multiplied by 1,000,000, which is the same as 1,500,000.
Dividing 395 by 1,500,000 we get 0.0002633333, or 2.633333e-4, which is another way of putting it.
