Math 9
posted by Molly .
My family went to starbucks. We ordered 3 drinks. My daughter's drink was .90 cents less than my drink and my sons drink was $2.20 more than my drink. The total bill was $12.90. How much was each drink? Use algebra.
Please help me, thanx

lets call your drink cost x
your sons y
and daughters Z
so x+y+z=12.9
and y=x+2.2
and z=x0.9
so x+x+2.2+x0.9=12.9
solve for x
you get 3x=11.6
x=3.867