very hard maths question

Question

a = b + 12

b = c + 4

write an equation to show the relationship between c and a

Answer 1

For a = b+12 where b=c+4,

write a = (c+4)+12.

Then a=c+16 or c=a-16.

Note that b was taken out of a = b+12 and (c+4) was put in b's place.