Ineed with a math question, could someone me?

1.) find the length and width of a rectangular sandbox, where the length is 3 feet longer than its width if you are building it with 30 feet of lumber.

Assume that 1400 births are randomly selected and 1378 of the births are girls. use subjective judgment to describe the number of girls as significantly high, significantly low, or neither significantly low nor significantly high. choose the correct answer below. a. the number of girls is neither significantly low nor significantly high. b. the number of girls is significantly high. c. the number of girls is significantly low. d. it is impossible to make a judgment with the given information.

3x = 729 solve for x plz . it's urgent. will mark

Solve the equation for b: a= (1/2)(b)(h)