(4 x 10^4) x (2 x 10^-5)
A) 8 x 10^1
B) 8 x 10^-1
C) 2 x 10^9
D) 6x 101-1.

B) 8•10^-1

Use the commutative property to reorder the terms.
(4•2)•(10^4 • 10^-5 )

Multiply the numbers. Multiply the terms with the same base by adding their exponents.
8•10^4-5

Calculate the difference and you get 8•10^-1

Hope this helps ʕ•ᴥ•ʔ

Sis less than or equal to 75 (bottom left)