10 because if you 3 with 7 I will make 10
Did I blow your mind so hit that heart button
Answer:
Cost price=100%
Step-by-step explanation:
This is an arithmetic sequence with the common difference being 1
and if u have 1 cent on day 1 and 2 cents on day 2....then on day 40, u would have 40 cents....but we need the sum of all the days..
the sum of an arithmetic sequence can be found using the formula :
sn = n(a1 + an) / 2
n = number of terms = 40
a1 = first term = 1
an = last term = 40
now we sub
s(40) = 40(1 + 40) / 2
s(40) = 40(41)/2
s(40) = 1640/2
s(40) = 820.....820 cents = $ 8.20 <== the sum
