Question 1131951
x = Andre's age
{{{6x+9=87}}}
The +9 in this equation is just all of the numbers in your original equation added together.
{{{6x=78}}}
{{{x=13}}}
(x) represents Andre's age
(x+3) Andre's age + 3 (brother)
(x-2) Andre's age - 3 (sister)
3(x+3)-1 Andre's age + 3 to get brother's age.  Times 3 subtract 1 to get Mom's age