22
Step-by-step explanation:
For simplicity, let
x = teary smiley
y = tongue smiley
z = plain smiley
So now our system of equations is
[tex]x + x + x = 12\:\:\:\:\:\:(1)[/tex]
[tex]y + z + x = 18\:\:\:\:\:\:\:(2)[/tex]
[tex]z + z + y = 22\:\:\:\:\:\:\:(3)[/tex]
[tex]z + y + 2x= ??\:\:\:\:\:\:(4)[/tex]
From Eqn(1), we plainly see that
[tex]3x = 12 \Rightarrow x = 4[/tex]
Now subtract Eqn(2) from Eqn(3) to get
[tex](2z + y) - (y + z + x) = 22 - 18[/tex]
[tex]\Rightarrow z - x = 4[/tex]
But we know that [tex]x = 4[/tex], which then gives us [tex]z = 8.[/tex]
Using the values of [tex]x[/tex] and [tex]z[/tex] in Eqn(2), we find that [tex]y = 6.[/tex] Now that we the values of all the variables, use them in Eqn(3) and we'll get
[tex](8) + (6) + 2(4) = 22[/tex]
