Let x the number of quartes and y the number of nickels
So (1) x + y = 47
Solve for x
x = 47 - y
Then .25x +.05 =4.95
It is better if you multiply both sides by 100 to get rid of the decimal
100(.25x +.05) = 100(4.95)
(2) 25x + 5y = 495
Replace the first x value in the second equation
(2) 25x + 5y = 495
25(47 - y ) + 5y = 495
Then solve the equation for y
1175 - 25y + 5y = 495
-25y + 5y = 495 - 1175
-20y = -680
y = -680/ -20
y = 34 nickels
Replace this y value in the x equation
x = 47 - y
x = 47 - 34
x = 13 quarters