Answer:
23. a-T b-F 
24. Words- *3* times the number of *feet*
 Variable- Let *y* represent the number of *yards*
 Model- (I can't do it)
 Expression- The number of feet in*3* yards is given by the expression *3y*
25. 7.8
26. 8.3
27. 14.5
28. Yes. The communitive property tells us that we can switch any two numbers in a multiplication or addition problem
*I did that page like a month ago*