Phil has 50 nickels and dimes worth $4.15. how many dimes does he have

Phil has 33 dimes, and 17 nickels

Step-by-step explanation:

Let number of nickels be X, and dimes be Y.

X + Y = 50.

Since nickels stand for 5 cents, or 0.05 dollars, and dimes are 10 cents, or 0.10 dollars, we can also write the total worth as:

0.05*X + 0.10*Y = 4.15

Multiply this last equation by 20:

20*0.05*X + 20*0.10*Y = 20*4.15

Simplify:

X + 2*Y = 83

Subtract the first equation (X + Y = 50) from this one:

Y = 33.

Thus Phil has 33 dimes, and 17 nickels.