(leave the 15 alone for the duration of the sum)
= 5*675 - 5*3*210 - 210 ------------------------------ time's out bracket
=5*675 -210(5*3 +1) ---------------------------- took out common "-210" out of last
two terms'
= 5*675 -210(15+1)
= 5*675 -210(16)
=5*675 -210*16