SOLUTION: A postal clerk sold some $.34 stamps and some $.23 stamps. Altogether, 15 stamps were sold for the total cost of $4.44. How many of each type of stamp were sold?
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-> SOLUTION: A postal clerk sold some $.34 stamps and some $.23 stamps. Altogether, 15 stamps were sold for the total cost of $4.44. How many of each type of stamp were sold?
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You can put this solution on YOUR website! Let the number of $.34 stamps =
Let the number of $.23 stamps =
given:
(1)
(2)
Multiply both sides of (1) by and
subtract from (2)
(2)
(1)
------------------------------
(2)
(1)
And, since
(1)
9 of the $.34 stamps were sold and
6 of the $.23 stamps were sold
check:
(2)
OK
You can put this solution on YOUR website! LET X BE THE NUMBER OF $0.34 STAMPS
LET Y BE THE NUMBER OF $0.23 STAMPS
SYSTEM OF LINEAR EQUATIONS
a) ($0.34)X + ($0.23)Y = $4.44
b) X + Y = 15
SOLVING
a) (0.34)X + (0.23)Y = 4.44
b) (-0.34)X - (0.34)Y = -5.10 <---- MULTIPLY BY -0.34 TO ELIMINATE X
YOU WILL GET A NEW EQUATION
c) -0.11Y = -0.66
IF YOU SOLVE FOR Y, THEN YOU WILL GET Y= 6
TO FIND X YOU TAKE THE VALUE OF Y AND SUSTITUTE IN THE ORIGINAL EQUATION
b) X + Y = 15, ---> X + 6 = 15; THEN X = 9
THE ANSWER WILL BE:
9 STAMPS OF $0.34, AND 6 STAMPS OF $0.23 WERE SOLD
