Question

Brenda has a balance of d dollars in her piggy bank. Explain what value(s) d may have if d = 28

Answer 1

Not sure what you're asking!  
Brenda has a blance of 38 dollars in her piggy bank.  What exactly do you still need to learn / know?

She might have 3-$10 bills, 1-$5 bill and 3-$1 bills.  Other combinations are possible.