A jar contains only pennies, nickels, dimes, and quarters. There are 25 pennies, 21 dimes, and 29 quarters. The rest of the
coins are nickels. There are 92 coins in all. How many of the coins are not nickels? If n represents the number of nickels in the jar, what equation could you use to find n?
"There are 25 pennies, 21 dimes, and 29 quarters", so there are 25+21+29 = 75 coins so far. This is the amount of coins that aren't nickels. The rest are nickels, which is some amount n. This adds to the 75 to get 75+n. Set this equal to 92 because there are 92 coins in all. That's how we end up with 75+n = 92.
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Extra info
The equation 75+n = 92 is the same as n+75 = 92. Subtract 75 from both sides to isolate n. You should get n = 17 after doing so.
