Robert sells 3 packages of cookie dough and 8 packages of pie dough for $35. Phil sells 6 packages of cookie dough and 6 packages of pie dough for $45. How much does each type of dough cost?
Just for shorting will call the cookie dough
We know Robert sold
To try to get to how much each cost, we need to put aside one of 'dough'; we do so by making one of the doughs even and then eliminate it (for now)
And if we put them together and subtract one by one,
Now we can return to the dough we left aside. And this time we already know how much pie dough cost so we put this, in case of Phil
And we left with this