math
posted by tai .
the 6th grade has 5 days to sell tickets to a talent show. The students predict that each day they will sell 10 fewer tickets than the day before. How many must they sell on the first day if they want to sell 200 tickets?
 do I divide 10 by 200 that would not make sense
please try to help me thanks

You are probably studying arithmetic sequences and series
let the first term be a
common difference is 10
and the number of terms is 5
S_{n} = (n/2)[2a + (n1)d]
200 = (5/2)[2a + 4(10)]
400 = 5[2a  40]
400 = 10a  200
600 = 10a
a = 60
So on the first day they must sell 60 tickets
check: 60 + 50 + 40 + 30 + 20 = 
assume that they will sell x tickets on the first day.
Sale on second day will be x10
third day x20
fourth day x30
fifth day x40
if we add them all up
x+x10+x20+x30+x40=200
5x100=2==
5x=300
x=60
so they have to sell 60 on the first day
50 on the second
40 on the third
30 on the fourth
and 20 on fifth day. 
find the difference using model subtraction with renaming

The product of a number and seven increased by twentythree is equal to one hundred seven.

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