Help! giving brainlest! Which advancement in mathematics contributed to improvements in algebra?

the use of formulas to show data
the use of vertical and horizontal axes
the development of multiplication
the substitution of letters for unknown numbers

hhghkkggcvbkkjvhkiuvvb

6 units. ab and lo are congruent sides, and if ab= 6 units, then lo would be the same.

john maynard keynes developed new economic theories in response to the : b) great depression of the 1930s. his theories are so important that they are known as "keynesianism". in his works he supports the idea of a government with deeper involvement and intervention to end the great depression.

to keep us neatruel and not get involved in any wars

he assumed control of treaty negotiations with a hostile power