9a - [7 - 5 (7a - 3) ]

a = 1/2

Step-by-step explanation:

Solve for a:

-7 + 9 a + 5 (7 a - 3) = 0

5 (7 a - 3) = 35 a - 15:

35 a - 15 + 9 a - 7 = 0

Grouping like terms, 35 a + 9 a - 15 - 7 = (9 a + 35 a) + (-7 - 15):

(9 a + 35 a) + (-7 - 15) = 0

9 a + 35 a = 44 a:

44 a + (-7 - 15) = 0

-7 - 15 = - 22:

44 a + - 22 = 0

Add 22 to both sides:

44 a + (22 - 22) = 22

22 - 22 = 0:

44 a = 22

Divide both sides of 44 a = 22 by 44:

(44 a) / 44 = 22/44

44/44 = 1:

a = 22/44

The gcd of 22 and 44 is 22, so 22/44 = (22*1) / (22*2) = 22/22*1/2 = 1/2:

Answer: a = 1/2