Let's set up some simultaneous equations. Let the number of nickels be n, and the number of quarters be q. Now I'm from England so I had to look up the value of a nickel (I could guess the quarter though to be 25c), but apparently it's 5c
Okay we know that the total value of the coins is 150. This gives:
25q + 5n = 150
Rearranging to make n the subject:
n = 30 - 5q
Next, we use the second statement:
n = 2q - 5
Substituting this into the first equation:
2q - 5 = 30 - 5q
7q = 35
q = 5
Putting this value for q into the first equation:
n = 30 - 5(5) = 5
Hence he has 5 of each coin. I hope this helps :)
