11. the formula for finding a number that's the square root of the sum of another number n and 6 is a. x = √n + 6. b. x = √n + 6. c. x = √n + √6. d. x = √n6.

-14 is the answer

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step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm