Answer:
16 5c coins
34 10c coins
Step-by-step explanation:
(I prefer to use whole numbers)
5x + 10y = 420
x+y=50
multiply the bottom problem by -5
5x +10y =420
-5x -5y = -250
combine the problems
5y = 170
divide by 5
y = 34
that means x = 16
34 10c coins
16 5c coins
-- Gage Millar, Algebra 1/2 tutor