In a class of 40 students, 5 like neither Nokia nor
Techno. 30 like Techno and Nokia. How many
students like only Nokia if altogether 35 like Techno?

The number of students that like only Nokia

Step-by-step explanation:

consider N the number of students who like Nokia → N=?

               T the number of students who like Techno → T=35

Statement 1: In a class of 40 students, 5 like neither Nokia nor Techno

we can translate it like this: 35 student like Nokia or Techno

we can note it like this : T∪N= 35

Statement 2: 30 like Techno and Nokia

we can note it : T∩N = 30

using a rule concerning the number of element of a set :

T∪N = N + T - T∩N

then

35 = N + 35 - 30

⇒ N - 30 = 0

⇒ N = 30

answer: the anser is 3

step-by-step explanation:

c- 2o is equal to 9

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for