Answer:
z is equal to 18.5
Step-by-step explanation:
When an equation is in the format a/b = c/d, the quickest way to simplify it is to cross multiply. Each side is multiplied by the other sides denominator, eliminating the division:
[tex]\frac{7}{z-1} = \frac{9}{z + 4}\\7(z + 4) = 9(z - 1)\\7z + 28 = 9z - 9\\7z - 9z = -9 - 28\\-2z = -37\\z = 37/2\\z = 18.5[/tex]
So z is equal to 18.5
