First, we need to convert the scientific notation to its standard form.
6) 2 x 10⁴ is 20000
9 x 10⁴ is 90000
3 x 10³ is 3000
20,000 + 90,000 - 3,000 = 110,000 - 3,000 = 107,000
107,000 in scientific notation is 1.07 x 10⁵
7) 4 x 10⁻⁵ is 0.00004
2 x 10⁻⁵ is 0.00002
3 x 10⁷ is 30000000
(0.00004 + 0.00002) ÷ 30,000,000 = 0.00006 ÷ 30,000,000 = 0.000000000002
0.000000000002 in scientific notation is 2 x 10⁻¹²
8) 5.476 x 10⁷ is 54,760,000
0.5476 x 10⁸ is 54,760,000
5.476 x 10⁷ = 0.5476 x 10⁸