Question 858139
Y + 18 = D [Dudley needs 18 to match Dolores' collection.]
Y + D = 184
Substitute the known value of D from the first equation into the second.
Y + (Y+18) = 184
2Y + 18 = 184
Subtract 18 from each side.
2Y = 166
Y = 83.  Dudley has 83.
.
Let's make certain:
83 + 18 =101 (Dolores' amount)
101 (Dolores) + 83 (Dudley) = 184
Success!