Alejandria has four shirts and three pairs of pants. she says that she has seven possible combinations.

False, there are 12 possible combinations.

Step-by-step explanation:

Each pair of pants matches to each shirt.  

She has 3 pairs of pants (1, 2, & 3) and 4 shirts (A, B, C, & D).

Here are all of the combinations:

           1A       1B       1C         1D

          2A      2B       2C        2D

          3A      3B       3C        3D

There are 3 pants × 4 shirts = 12 different combinations

c.35

step-by-step explanation:

8+13=21

21+8=29

29+6=35

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.