If I understand your sequence, then this is the "closed form" of the sequence:
a_n = 63 - 4 n
Sum = (59, 55, 51, 47, 43, 39, 35, 31, 27, 23, 19, 15, 11, 7, 3) = 465
Answer:
11/15 km
Step-by-step explanation:
Simply sum the areas:
2/5 + 1/3 = (6 + 5)/15 = 11/15
100/5-4
He spend 100 total, and he spend $5 on each book. So 100/5 would give him how many books total that he bought. If he bought 4 extra you need to subtract that to find out how many books he originally wanted to buy.
a-3
3(2a–1)−5a =
distribute
3*2a -3*1 -5a=
6a -3 -5a
combine like terms