document.write( "Question 699611: Galina spent $3.60 for stamps to mail packages. Some were 30 cents and the rest were 20 cents. The number of 20 cent stamps is two less than the 30 cent stamps. How many stamps of each kind did Galina buy? \n" ); document.write( "

Algebra.Com's Answer #431442 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = number of 30 cent stamps she bought
\n" ); document.write( "Let $\"+b+\"$ = number of 20 cent stamps she bought
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+30a+%2B+20b+=+360+\"$ ( in cents )
\n" ); document.write( "(2) $\"+b+=+a+-+2+\"$
\n" ); document.write( "---------------
\n" ); document.write( "Substitute (2) into (1)
\n" ); document.write( "(1) $\"+30a+%2B+20%2A%28+a+-+2+%29+=+360+\"$
\n" ); document.write( "(1) $\"+30a+%2B+20a+-+40+=+360+\"$
\n" ); document.write( "(1) $\"+50a+=+400+\"$
\n" ); document.write( "(1) $\"+a+=+8+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(2) $\"+b+=+a+-+2+\"$
\n" ); document.write( "(2) $\"+b+=+8+-+2+\"$
\n" ); document.write( "(2) $\"+b+=+6+\"$
\n" ); document.write( "She bought 8 30 cent stamps and 6 20 cent stamps
\n" ); document.write( "check:
\n" ); document.write( "(1) $\"+30%2A8+%2B+20%2A6+=+360+\"$
\n" ); document.write( "(1) $\"+240+%2B+120+=+360+\"$
\n" ); document.write( "(1) $\"+360+=+360+\"$
\n" ); document.write( "OK
\n" ); document.write( " \n" ); document.write( "

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