Can anyone me with these 3 problems?

1. let f(x) = 4x+7 and g(x) = 3x-5. find (g.)

a. -64
b.-61 < i think it's this one
c.-9
d.-32

2. let f(x)=3x+5 and g(x)=-4x+7. find (f.)

a. 74
b. -7
c. 23 < i think it's this one
d. 35

3. let f(x)=4x+3 and g(x)=-2x+5. find (g. f)(5)

a.-17 < i think it's this one
b.23
c.-5
d.-41

would be very !

Solve the system of equations. y= 2x y= x^2 - 15

Afarmer has a large field that is x feet in length. he wants to fence in a rectangular section in the middle of the field , leaving a length of 100 feet of open field behind each end of the fenced rectangle.he also wants the width of the fenced-in space to be 100 feet less than its length. find the expressions to represent the length and width of the fenced section of the field

On #16 : explain how factoring a trinomial, ax^2+ bx+ c, when a does not equal 1 different from factoring a trinomial when a = 1.