Question

5a - 3/9 = 3
7b - 1 = a - 21
use this to help you find the b

Answer 1

.....5a - 3/9 = 3

⇒5a = 3 + 3/9

⇒5a = 10/3

⇒a = 10/15 = 2/3

7b - 1 = a - 21

⇒-a=-21+1-7b

⇒-a = -20-7b

we replace a :

-2/3 = -20-7b

7b = -20 +2/3

7b = -58/3

b= -58/21

we check

5a-3/9 =3

5*2/3 - 3/9 = 3

7b-1 = a-21

7b-1 = 7*-58/21 -1 =-61/3

a-21 = 2/3 -21 = - 61/3

Explanation: