I can not get he correct answer -10.

Question

-3/3{a+c(b+5)-(-6+a)}
a=1, b=-6, c=-4

Answer 1

starting with
-3/3{a+c(b+5)-(-6+a)}
= -3/3{1+(-4)((-6)+5)-(-6+1)}
let's work our way from the inside out:
-3/3{1+(-4)(-6+5)-(-6+1)}
-3/3{1+(-4)(-1)-(-5)}
-3/3{1+4+5)}
-3/3{10}
-1(10)
-10

Note that the division is done first, then the multiplication, left-to-right