Let there be m dimes and n nickels in the jar.
Remember dimes are worth 10 cents and nickels 5 cents.
Total number of coins is 135, so m + n = 135
Total amount is $11.40 or if you don't like decimals 1140 cents, so 10m+ 5n = 1140
m + n =135
10 m + 5 n = 1140
To make things easy I can multiply the first equation by 10 and use the elimination method.
10 m + 10 n = 1350
10 m + 5 n = 1140
5n = 210 and diving I get n = 42.
Since I know m + n = 135, then m = 135 - n = 135 - 42 = 93.
Thus, we have 93 dimes and 42 nickels.
Always good to note what the question asks so you can give the right interpretation after finding the variables. You also can check that the total adds up right to be sure.
