I need help with the questions in the files

okay im sorry but i can only help with the first page so im going to use the first equation as an example. when it tells you what x equals in this case four you put it in place of the variable and put it all together and see if those two numbers egual the amount given. so here it written out:

x +11=15 x= 4

4+ 11 + 15.

in this case yes the given numbers equal the amount.

really hope this helped you!

Step-by-step explanation:

the answer to this question is "motor unit"