If Joe adds 2 nickels to his second amount, he will have 3 times the dimes he has in the first amount. That is, the two amounts will now differ by twice the number of dimes Joe has. ($10.45 + 2*.05) - $8.55 = 2*dimes $2.00 = 2*dimes $1.00 = dimes ($8.55 - $1.00)/$.05 = 151 Joe has 10 dimes and 151 nickels.
Check $3.00 + 149*$.05 = $3.00 + $7.45 = $10.45
Check $3.00 + 149*$.05 = $3.00 + $7.45 = $10.45