Help me with this math problem?

Question

Dennis plans to use 1150 ft of fence to enclose the rectangular pasture. One side borders a river where there is already a thick hedge it needs no fencing.
The diagram is a rectangle with width x.

a. let x be the width. write an expression for the length in term of x
b. write an expression for the area of the pasture in terms of x
c. suppose the pasture must enclose at least 60,000 sq ft. write a sentence (as a sentence in math not a sentence like this one.) relating the area expression in part b to the area the pasture must enclose.

I have a and b but i want to check them since they're related and i completely don't understand c, can you clear thing sup a bit for me?

Answer 1

a)
Assuming the river/hedge is a LENGTH...
length = 1150 - 2x

b)
Area = length * width
= (1150 - 2x)(x)
= 1150x - 2x^2

c)
1150x - 2x^2 >= 60000

Answer 2

l = 1150-2x
A = x(1150-2x) = 1150x - 2x^2
1150 x -2x^2 =/> 60,000 ft^2