The cost of using light construction equipment is $1,100 for 3 hours or $1,700 for 5 hours. which of the following functions could represent the cost, c(x), of using the equipment for x hours?

Assuming that the cost follows a linear form, thus to obtain the function we shall proceed as follows:
Linear equation is given by:
y=ax+b
where:
a=slope
b=y-inntercept
the equation is given by:
a(x-x1)=y-y1
but from the points given
a=(1700-1100)/(5-3)=300
thus the equation will be:
300(x-3)=y-1100
thus the function will be:
y=300x-900+1100
hence:
C(x)=300x+200

C(x)=300x+200

and surely you know how much that is.