Question 885192
let 
a=a1
b=a2
c=a3
b=2a + 3 
c=4b + 3
z=a+b+c
z=a+2a+3+4b+3
z=a+2a+3+4(2a+3)+3
z=a+2a+3+8a+12+3
z=a+2a+3+8a+12+3
z=11a+18
a1 + a2 + a3 =11a1+18