Question 1004829: a bank teller counted P100 and P50 bills. this totaled to 117 bills worth P9950. how many bills of each type did she have? Found 2 solutions by Edwin McCravy, AnlytcPhil:Answer by Edwin McCravy(20056) (Show Source):
Let the number of P100's be x
Let the number of P50's be y
Value Value
Type Number of of
of of EACH ALL
bill bills bill bills
-------------------------------------------
P100s x P100 P100x
P50s y P50 P50y
-------------------------------------------
TOTALS 117 ----- P9950
The first equation comes from the second column.
x + y = 117
The second equation comes from the last column.
100x + 50y = 9950
So we have the system of equations:
.
We solve by substitution. Solve the first equation for y:
x + y = 117
y = 117 - x
Substitute (117 - x) for y in 100x + 50y = 9950
100x + 50(117 - x) = 9950
100x + 5850 - 50x = 9950
50x + 5850 = 9950
50x = 4100
x = 82 = the number of P100s.
Substitute in y = 117 - x
y = 117 - (82)
y = 35 P50s.
Checking: 82 P100s is P8200 and 35 P50s is P1750
That's 117 bills.
And indeed P8200 + P1750 = P9950
Edwin
The problem can also be done using only one
unknown or variable:
Let the number of P100s be x
Then the number of P50s, using
ONE PART = TOTAL MINUS OTHER PART,
is 117-x.
Value Value
Type Number of of
of of EACH ALL
bill bills bill bills
-------------------------------------------
P100s x P100 P100x
P50s 117-x P50 P50(117-x)
-------------------------------------------
TOTALS 117 ----- P9950
The equation comes from the column on the right
100x + 50(117-x) = 9950
100x + 50(117-x) = 9950
100x + 5850 - 50x = 9950
50x + 5850 = 9950
50x = 4100
x = 82 = the number of P100s.
The number of P50s is 117-x or 117-82 or 35 P50s.
Checking: 82 P100s is P8200 and 35 P50s is P1750
That's 117 coins.
And indeed P8200 + P1750 = P9950
Edwin