#color(red)("Using first principles.")#
Given:#color(brown)(" "-2(u+4)-6=22)#
Multiply everything inside the bracket by -2
Note that when you multiply, if the signs are different the answer is negative.
Also if the signs are the same when you multiply the answer is positive.
#" "color(brown)(-2y-8-6=22)#
#" "color(brown)(-2y-14=22)#
Add #color(blue)(14)# to both sides
#" "color(brown)(-2y-14color(blue)(+14)" "=" "22color(blue)(+14))#
But#" " -14+14=0#
#" "color(brown)(-2y+0" "= " "36)#
Multiply both sides by (-1)
#" "color(brown)(+2y" "= " "-36)#
Divide both sides by #color(blue)(2)#
#" "color(brown)(2/(color(blue)(2))xxy" "= " "-36/(color(blue)(2))#
#" "color(brown)(y" "=" "-18)#
