5x + y = 9....multiply by 7
10x - 7y = -18
----------------
35x + 7y = 63 (result of multiplying by 7)
10x - 7y = -18
----------------add
45x = 45
x = 45/45
x = 1
5x + y = 9
5(1) + y = 9
5 + y = 9
y = 9 - 5
y = 4
solution is : (1,4)
=========================
-4x + 9y = 9
x - 3y = -6 ....multiply by 4
----------------
-4x + 9y = 9
4x - 12y = -24 (result of multiplying by 4)
---------------add
- 3y = - 15
y = -15/-3
y = 5
x - 3y = -6
x - 3(5) = -6
x - 15 = -6
x = -6 + 15
x = 9
solution is : (9,5)
Step-by-step explanation:
In the recursive formula an = an−1 + 5

Suppose if a_5 is the nth term then previous term is a_4
To get the previous term we need to subtract 1 from the n
So a_n is the nth term
is the previous term
Here 5 represents the common difference between two terms
So value of previous term is represented by

Answer : 
Answer B is correct. Sum is the answer to an addition problem, so sum of 8 and 2 would be 8+2.
The formula for circumference is

or

. We have a diameter for the semicircle, so let's use the diameter formula.

which is either

or C = 5.338 if we multiply pi in as 3.14. BUT this is only half a circle, so we only have half that distance around the outside. Therefore, the circumference of half this circle is 2.669 cm. But we need to add the 24 mm in. 24 mm in centimeters is 2.4 cm. So 2.669 + 2.4 = 5.069
Umm im not sure maby like 1+1 or sum