Remember that a dime is worth 10 cents and a quarter is worth 25 cents and $4.60 is 460 cents.
Let D = the number of dimes and Q = the number of quarters.
Now let's translate the English into math. . .
there are 28 coins in all--> D + Q = 28 so D = 28 - Q
they are worth 460 cents--> 10D + 25Q = 460
Now substitute 28-Q for D--> 10(28-Q) + 25Q = 460
280 - 10Q + 25Q = 460
Combine like term. . .
15Q = 180
Divide both sides by 15--> Q = 12
So D = 16
