1) It should be the opposite of what you put; 9 - n
2) Correct; y/22
3) Correct; 57 + b
4) Correct; 2/3x
5) Correct; c - 18
6) Correct; 2m + 25
7) Should be opposite of what you put; 8/2z
8) Correct; 2 + r²
9) I would just make the expression 40 - d since that's what it looks like your homework wants you to do; 40 - d
10) Correct; 1 + b
11) Correct; c/4
12) Not sure what you did there, but all you have to do to convert hours into minutes is to multiply the hours by 60; 60h
13) 75/5 = 15; Unit rate:
![(\$15)/(1~video~game)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/ap3hl6htc6x88pfrgl7beb58t39bz922lm.png)
14) 600/8 = 75; Unit rate:
![(75~students)/(1~class)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/u3h7rrx6f2xqq5rtmxyd291cyprj0wfaeu.png)
15) 32/4 = 8; Unit rate:
![(8~pencils)/(1~box)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/bfia1r7xdkayvffgw8o6xv776keep46kbu.png)