Question

Please help , also I need to show work and do it ASAP

Answer 1

You probably would have received help faster had you posted only one problem at a time.  Try that next time you want help.

Regarding your first question:  "How many different ways can you obtain a total of 50 cents with 7 or fewer coins?"  I'd suggest you write out as many combinations of 7 or fewer coins as you can that add up to 50 cents.  

Examples:  
Five dimes (5 coins) add up to 50 cents.
Three dimes and four nickels (7 coins) add up to 50 cents.

Keep going until you've run out of possibilities.