Answer:
16
Step-by-step explanation:
Lets assume x is Elgas' age
And y is Alvins age
we know that alvin is 11 years younger than Elga which means,
x=y+11
and the sum of their age is 43
x+y=43
solve it and you get 16
15 - natural (1,2,3...15....) and integers (...-2,-1,0, 1,2,...15,...)
For a you have to solve 2 solutions , first 2x=12
6=x then you plug that back in, 12+8y=12
8y=0
y=0
(6,0)