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Work Shown:
x = number of $2 coins
y = number of $10 coins
x+y = 43 coins total
x = 43-y
2x = value of just the $2 coins only
10y = value of all the $10 coins only
2x+10y = total value of all coins mentioned
This value must be greater than $278, so,
2x+10y > 278
2( x ) + 10y > 278
2(43-y)+10y > 278
86-2y+10y > 278
8y+86 > 278
8y > 278 - 86
8y > 192
y > 192/8
y > 24
The smallest y can be is y = 25.
We need at least 25 coins worth $10 each.
