add formula
add formula
Revert "add formula"

This reverts commit 7f610b1aa83bc6977027783196fd25b72273f368.
Revert "Revert "add formula""

This reverts commit 5b66cf595d1d3042099971efca3b27542878ff85.
Revert "add equation"

This reverts commit 4caa24d96bc4df32f5b1282d7c680d50be1f6725.

Conflicts:
	presentation.svg
merge conflict
remove equation
add formula