25. (a) The sum of the first n terms of a sequence is given by S, = n(n+2).
Find:
(1) the sum of the twentieth,
twenty-first and twenty-second
terms of the sequence;
(ii) the first three terms of the
sequence.
(b) The sum of the first twenty-one
terms of a linear sequence (A. P.) is
28, and the sum of the first twenty-
eight terms is 21. Find which term of
the sequence is 0 and also the sum
of the terms preceding it.
whose​

add the numbers under frequency to find the total number:

5 + 8 +7 + 4 + 0 +1 = 25

the answer is 25.

c = 0.429t

step-by-step explanation:

the constant rate at which carlos harvests cassava is 35 minutes per 15 cassavas 15/35 = 0.429 cassava per minute

therefore, an equation that models the number of cassava (c) that harvest carlos in a time (t) is the following:

where t is the time in minutes.

this means that when 35 minutes have elapsed 15 cassava have been harvested, at 70 minutes 30 cassava have been harvested and so on.