SOLUTION: April has 100 stamps - some of which are worth 20 cents each and the rest are worth 17 cents each. If the total value of the stamps is $18.83, how many 17 cnets stamps does april h

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Question 666381: April has 100 stamps - some of which are worth 20 cents each and the rest are worth 17 cents each. If the total value of the stamps is $18.83, how many 17 cnets stamps does april have?
I have tried .2(50y)+.17y = 18.83 so far
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = number of 20 cent stamps
Let +b+ = number of 17 cent stamps
given:
(1) +a+%2B+b+=+100+
(2) +.2a+%2B+.17b+=+18.83+
-----------------------
(2) +20a+%2B+17b+=+1883+
Multiply both sides of (1) by +17+
and subtract (1) from (2)
(2) +20a+%2B+17b+=+1883+
(1) +-17a+-+17b+=+-1700+
+3a+=+183+
+a+=+61+
and
(1) +61+%2B+b+=+100+
(1) +b+=+100+-+61+
(1) +b+=+39+
61 = number of 20 cent stamps
39 = number of 17 cent stamps
check:
(2) +.2%2A61+%2B+.17%2A39+=+18.83+
(2) +12.2+%2B+6.63+=+18.83+
(2) +18.83+=+18.83+
OK