S=number of 6 cent stamps t=number of ten cen stamps e=number of 8 cent stamps w=number of 20 cents stamps=2
cost=500 cents 6s+10t+8e+20w=500 w=2 since two 20 cent stamps wer bought 6s+10t+8e+40=500 minsu 40 both sides 6s+10t+8e=460 divide both sides by 2 to simplify 3s+5t+4e+230
also 10 more 6 cent than 10 cent s=10+t
8 cent stamps is 3 times 10 cent stamps e=3t
sub s=10+t e=3t
3(10+t)+5t+4(3t)+230 30+3t+5t+12t=230 30+20t=230 minus 30 20t=200 divid 20 t=10
sub back s=10+t s=10+10 s=20
e=3t e=3(10) e=30
20 six cent 30 eight stamp 10 ten cent 2 twenty cent
