Question 28297
Let number of dimes be x
Let number of quarters be y
x+y=146
y=146-x (subsitution)


Dime value x 100 = 10 
Quarter value x 100 = 25
Total value x 100 = 2450


10x+25y=2450
10x+25(146-x)=2450
10x-25x+3650=2450
-15x=-1200
x=80


y=146-80
y=66


Hence, there were 80 dimes and 66 quarters.
Paul.