Subtract: (8.1×105)−(3×104)(8.1 \times 10^5) - (3 \times 10^4)(8.1×105)−(3×104).
7.8×1057.8 \times 10^57.8×105
5.1×1055.1 \times 10^55.1×105
5.1×1015.1 \times 10^15.1×101
7.8×1047.8 \times 10^47.8×104