Consider that the power from the solid rocket boosters can be written as follow in scientific notation:
9,750,000,000 = 9.75*10^9
The previous equivalence is because to obtain 9.75 we move nine positions the decimal point.
Now, consider that power from the main engines is:
Power main engines = (total power) - (power solid rocket booster)
In order to subtract the power from solid rocket booster to the total power, it is necessary that total power is written with a factor 10^9 (the powers of 10 must be the same to simplify). You can write the total power as follow:
1.174*10^10 = 11.74*10^9
This is because if we move the decimal point one position to the right, we must also reduce the power of 10 by 1 unit.
Then, we have now:
Power main engines = 11.74*10^9 - 9.75*10^9
The previous numbers has the same factor (10^9). Subtract the coefficients and put the same factor:
Power main engines = 1.99*10^9
Hence, the power from the engines is 1.99*10^9
