Answer:
x = - 7
Explanation:
Express the diagrams in equation form with output y
A y = 5x - 4
B y = 3x + 8
Equate the right sides so that A is 3 times B
5x - 4 = 3(3x + 8) ← distribute parenthesis
5x - 4 = 9x + 24 ( subtract 9x from both sides )
- 4x - 4 = 24 ( add 4 to both sides )
- 4x = 28 ( divide both sides by - 4 )
x = - 7
As a check
A y = 5(- 7) - 4 = - 35 - 4 = - 39
B y = 3(- 7) + 8 = - 21 + 8 = - 13
then - 13 × 3 = - 39
The required input is x = - 7