Let x be the number of nickels he is holding.
His nickels are worth 5 * x = 5x cents.
He has x+4 dimes.
The dimes are worth 10 * (x+4)
The total worth of the nickels and dimes is 5x + 10*(x+4) = 70.
5x + 10x + 40 = 70
15x = 30
x = <<2=2>>2, Steve has 2 nickels in his hand.
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