How do i write fractions as a sum or difference

Afamily has five members. a mom, a dad, two sisters, & a brother. the family lines up single file. what is the probabillity that the mom is at the front of the line

Find the nonpermissible replacement for binthis expression.b2/5b +5

The cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?