Answer:He used five 40-cent stamps and eight 7-cent stamps.
Step-by-step explanation:
Let x represent the number of 40-cent stamps that he used.
Let y represent the number of 7-cent stamps that he used.
41 cents = 40/100 = $0.40
7 cents = 7/100 = $0.07
He uses 40-cent stamps and 7-cent stamps to pay $2.56 in postage. It means that
0.4x + 0.07y = 2.56
Multiplying through by 100, it becomes
40x + 7y = 256
7y = 256 -40x
We would test for corresponding values of x and y that satisfies the equation and they must be whole numbers.
If x = 4,
7y = 256 - 40 × 4 = 96
y = 96/7 = 13.71
If x = 5,
7y = 256 - 40 × 5 = 56
y = 56/7 = 8
Neil needs to mail a CD to friend, the amount he paid $2.56 in postage he used Five-40-cent stamps & Eight 7-cent stamps in total.
To find the number of each stamp he uses we need to find the amount for each 40cent stamp & 7cent stamp,
According the given question we will represent x & y as follows:-
x = Total number of 40-cent Stamps
y=Total number of 7-cent Stamps
[tex]\rm 41 cents = \dfrac{40}{100} =\$ 0.40\\\rm 7 cents =\dfrac {7}{100} = \$0.07[/tex]
Now, according to the statement wewill calculate.
[tex]\rm 0.4x + 0.07y = 2.56[/tex]
On multiplying by 100 we get,
[tex]\rm 40x + 7y = 256 \;\;\;\;\;\;\;\;\;\; ....................(1)\\7y = 256 -40x\;\;\;\;\;\;\;\;\;\; ....................(2)[/tex]
We will now further solve both equation and satisfies the values for x & y
On putting the value of [tex]x=4[/tex] in equation (2) we get,
[tex]7y = 256 - 40\times 4 = 96\\\;y = \dfrac{96}{7} = 13.71[/tex]
Again put the value of [tex]x=5[/tex] in equation (2) we get,
[tex]7y = 256 - 40 \times 5 = 56\\y = \dfrac{56}{7} = 8[/tex]
Therefore , He used five 40-cents and eight 7-cents in total.
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