It is given in the question that,
A sailboat has a triangular sail with an area of 30 square feet. the height of the sail is 7 feet more than the length of the base of the sail.
Let the length of the base be x, so height is
[tex](x-7)feet[/tex]
And formula of area of triangle is
[tex]A = \frac{1}{2}bh[/tex]
Substituting the values of Area, base and height,
[tex]30 = \frac{1}{2}x(x+7)[/tex]
Multiplying both sides by 2
[tex]60 = x^2 + 7x[/tex]
[tex]x^2+ 7x-60=0 \\ (x+12)(x-5)=0 \\ x=5 feet[/tex]
So the base is 5 feet and the height is 12 feet.