Answer:
number of twenty dollar bills = 8
number of fifty dollar bills = 9
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Work Shown:
T = number of twenty dollar bills
F = number of fifty dollar bills
T+F = 17, since there are 17 bills total
T+F-T = 17-T ... subtract T from both sides
F = 17-T .... we'll use this later
20T = value of all of the twenty dollar bills
50F = value of all the fifty dollar bills
20T+50F = total value in dollars
20T + 50F = 610
20T + 50(17 - T) = 610 ..... plug in F = 17 - F
20T + 50(17) + 50(-T) = 610 .... distribute
20T + 850 - 50T = 610
-30T + 850 = 610
-30T + 850 - 850 = 610 - 850 .... subtract 850 from both sides
-30T = -240
-30T/(-30) = -240/(-30) ... divide both sides by -30
T = 8
F = 17 - T
F = 17 - 8
F = 9
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we have T = 8 twenties and F = 9 fifties
20T = 20*8 = 160 dollars with just the twenty dollar bills
50F = 50*9 = 450 dollars with just the fifty dollar bills
160+450 = 610 dollars total
This confirms the answer.