Respuesta :

10 * 10^2 - 7.79* 10^3

they have to be to the same power to add or subtract

change 10*10^2 to proper scientific notation  (only 1 number before the decimal) 1*10^3

1*10^3 - 7.79*10^3 = (1-7.79) * 10^3=-6.79*10^3