Question

Can someone please help with this question?!

Answer 1

So in a proportion you multiply, in this case you have to combine the z with the 3 to create 3z.
12/24 

Answer 2

$\frac{z+3}{3} = \frac{8}{4}$

$\frac{z+3}{3} = 2$

$z+3 = 6$

$z=3$