We are informed that Stephen rewrites 3r - 18 = 27 as 3(r - 6) = 3(9). This is quite thoughtful of Stephen and it's an easier way to solve the question.

In this case, 3 is a common factor to 3r, 18 and 27. Therefore, we will then have: 3(r - 6) = 3(9).

Since 3 is a common base to both, we are more concerned with the values inside the brackets. This will be:

r-6 = 9

r = 9 + 6

r = 15

Check: 3r - 18

3(15) - 18 = 45 - 18 = 27

3 0

3 years ago

X + y + z = 7 2x − y + z = 7 3x − z = 2

soldi70 [24.7K]

A) X + y + z = 7
B) 2x − y + z = 7

C) 3x − z = 2
C) z = 3x -2 Substituting this into equations A) and B)


A) X + y + 3x -2 = 7
B) 2x − y + 3x -2 = 7 Adding A and B
3x + 6x -4 = 14
9x = 18
x = 2
Since x = 2 then
A) 2 + y + 6 -2 = 7
A) y = 1

A) X + y + z = 7
A) 2 + 1 + z = 7
z = 4

7 0

3 years ago

What's A-B if A={1,2,3,4,5} and B={4,5,6,7}​

What's A-B if A={1,2,3,4,5} and B={4,5,6,7}