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\(x\times\dfrac{5}{7}-3=18\)

\(x\times\dfrac{5}{7}=18+3\)

\(x\times\dfrac{5}{7}=21\)

\(x=21:\dfrac{5}{7}\)

\(x=\dfrac{147}{5}\)

X x 5/7 - 3 = 18

X x 5/7      = 18 + 3

X x 5/7      =21

X               =21 : 5/7

X               =147/5

2.He doesn't know he boat may take a trip around the island.

3.Phuong, Tuan and Hoa may build sandcastles on the beach.

4.My family and I will swim in the sea.

5.They'll be at the seaside on sunday.

2.He doesn't know he boat may take a trip around the island.

3.Phuong, Tuan and Hoa may build sandcastles on the beach.

4.My family and I will swim in the sea.

5.They'll be at the seaside on sunday. 

B = 2¹⁰⁰ - 2⁹⁹ + 2⁹⁸ - 2⁹⁷ + ... + 2²

B = ( 2¹⁰⁰ + 2⁹⁸ + ... + 2² ) - ( 2⁹⁹ + 2⁹⁷ + ... + 2³ )

B = ( 2¹⁰⁰ + 2⁹⁹ + 2⁹⁸ + 2⁹⁷ + ... + 2³ + 2² ) - 2( 2⁹⁹ + 2⁹⁷ + ... + 2³ )

B = ( 2¹⁰⁰ + 2⁹⁹ + 2⁹⁸ + 2⁹⁷ + ... + 2³ + 2² ) - ( 2¹⁰⁰ + 2⁹⁸ + ... +

2⁴ )

B = 2⁹⁹ + 2⁹⁷ + ... + 2³ + 2²

2²B = 2¹⁰¹ + 2⁹⁹ + ... + 2⁵ + 2⁴

4B - B = ( 2¹⁰¹ + 2⁹⁹ + ... + 2⁵ + 2⁴ ) - (  2⁹⁹ + 2⁹⁷ + ... + 2³ + 2² )

3B = 2¹⁰¹ + 2⁴ - 2³ - 2²

3B = 2¹⁰¹ + 16 - 8 - 4

3B = 2¹⁰¹ + 4

B = \(\dfrac{2^{101}+4}{3}\)