Answer:
me add me
Step-by-step explanation:
☆Concept:-
The Question is based on the law of exponents .
The law to be used in this question is
![\boxed{\sf a^m\times a^n=a^{m+n}}](https://tex.z-dn.net/?f=%5Cboxed%7B%5Csf%20a%5Em%5Ctimes%20a%5En%3Da%5E%7Bm%2Bn%7D%7D)
Solution:-
![\\ \tt\longmapsto (9\times 10^{-4})^2](https://tex.z-dn.net/?f=%5C%5C%20%5Ctt%5Clongmapsto%20%289%5Ctimes%2010%5E%7B-4%7D%29%5E2)
![\\ \tt\longmapsto 9^2\times 10^{-4(2)}](https://tex.z-dn.net/?f=%5C%5C%20%5Ctt%5Clongmapsto%209%5E2%5Ctimes%2010%5E%7B-4%282%29%7D)
![\\ \tt\longmapsto 81\times 10^{-8}](https://tex.z-dn.net/?f=%5C%5C%20%5Ctt%5Clongmapsto%2081%5Ctimes%2010%5E%7B-8%7D)
![\\ \tt\longmapsto 8.1\times 10^{-7}](https://tex.z-dn.net/?f=%5C%5C%20%5Ctt%5Clongmapsto%208.1%5Ctimes%2010%5E%7B-7%7D)
Answer: 2(12+8) +3
Step-by-step explanation: In the morning they made 12 + 8 airplanes = (12 + 8)
In the afternoon they doubled the number that they made in the morning = 2 (12 + 8)
Finally, you would add 3 to this for the ones that her brother made = 2 (12 + 8) + 3