Subtract seven more than twice a number from the square of one-third of the number you get zero

1/3squared (2x+7) = 0

1/9 (2x+7) = 0

2/9x+7/9=0

2/9x=-7/9

x=-7/2 or - 3 and 1/2

X=the number

the square of 1/3 the number = (x/3) ^2 = (x^2) / 9

7 more than twice the number=2x+7

2x+7 - ((x^2) / 9) = 0

2x+7 = (x^2) / 9

multiply both sides by 9:

18x+63=x^2

subtract 18x+63 from both sides:

x^2-18x-63=0

you can use the quadratic formula or factor it as

(x-21) (x+3) = 0

the number is - 3 or 21