With the aid of a properly-labeled diagram, explain what would happen automatically if total planned spending (C+I) in Economia (a closed economy

With the aid of a properly-labeled diagram, explain what would happen automatically if total planned spending (C+I) in Economia (a closed economy with no government) intersected the 45º line at a national income of $890 billion, but the economy temporarily found itself with national income of $900 billion.