Mario bought $5 worth of stamps at the post office. He bought ten more 6 cents stamps than 10 cents stamps. The number of 8 cents stamps was three times the number of 10 cents stamps. He also bought two 20 cents stamps. How many of each kind of stamp did he purchase?

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