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

The answer would be a i think

Yes, that is the correct formula. to solve this problem given the number of years, plug in the number of years for t and plug the whole thing into the