d+n=25 subtract d from both sides *(if your wondering what d and n are it stands for Dimes and Nickels)* n=25-d
0.10d+0.05= 1.85
0.10d+0.05(25-d)= 1.85
0.10d+1.25-0.05d= 1.85
0.05d = 0.60
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My answer: He has 12 dimes (d=12) and 25-12=13 so 13 nickels.. Hope this helps! :)