What dramatic changes in tools took place near the end of the paleolithic period?

At the end of the Paleolithic period a number of changes in tools happened. Firstly, they began to develop composite tools like a spear, for example. Furthermore, some specialized tools were created, such as bone needles for primitive sewing and  arrowheads, which were used for hunting. All in all, the majority of tools in that time were made either of stone or bones.

simplify brackets

8 - 2a - 7 = a + 40

simplify 8 - 2a - 7 to -2a + 1

-2a + 1 = a + 40

add 2a to both sides

1 = a + 40 + 2a

simplify a + 40 + 2a to 3a + 40

1 = 3a + 40

subtract 40 from both sides

1 - 40 = 3a

simplify 1 - 40 o -39

-39 = 3a

divide both sides by 3

-39/3 = a

simplify 39/3 to 13

-13 = a

switch sides

a = -13