Question

Given a+b=7 and a–b=3, find:
3^a/3^b

Answer 1

27

Explanation:

Find numbers that add up to 7.

0, 1, 2, 3, 4, 5, 6, 7

Which of those could subtract to get 3?

5 and 2

5 - 2 = 3

a = 5

b = 2

3^5 = 243

3^2 = 9

243 / 9 = 27

Answer 2

A=-2 and B=3

Explanation:

Step 1) Solve the first equation for A:

a+3b=7

a+3b-3b=7-3b

a+0=7-3b

a=7-3b

Step 2) Substitute (7-3b) for a in the second equation and solve for b:

2a=b-7 becomes:

2(7-3b)=b-7

(2*7)-(2*3b)=b-7

14-6b=b-7

14+7-6b+6b=b+6b-7+7

21-0=1b+6b-0

21=(1+6)b

21=7b

7b/7=21/7

=3

a=7-3b becomes:

a=7-(3*3)

a=7-9

a=-2