Answer :
f(x)=7-8x
f(-2)=7-8×(-2)
=7-(-16)
=7+16
=23
f(4)=7-8×4
=7-32
=-25
average=[23+(-25)]÷2
=(23-25)÷2
=(-2)÷2
=-1
f(-2)=7-8×(-2)
=7-(-16)
=7+16
=23
f(4)=7-8×4
=7-32
=-25
average=[23+(-25)]÷2
=(23-25)÷2
=(-2)÷2
=-1