9514 1404 393
Answer:
Explanation:
If all of Brent's coins were pennies, their value would be 1.63. The value is actually 4.42 -1.63 = 2.79 more than that. Replacing a penny by a dime increases the value by .09. Hence there must be 2.79/.09 = 31 replacements.
Brent has 31 dimes and 132 pennies.
_____
Solution using an equation
You can write an equation that solve the problem in basically the same way. Let the variable represent the number of coins of highest value: d = dimes. Then the value (in cents) of the collection is ...
1(163-d) +10d = 442
9d +163 = 442 . . . . . . . . . . simplify (note 9 is the difference in value; 163 is the value of all pennies)
9d = 442 -163 = 279 . . . . . . subtract 163
d = 279/9 = 31 . . . . . . . . . . divide by 9
Brent has 31 dimes and 163-31 = 132 pennies.