Let z be the required expression.
The given is
[tex]\frac{3}{14x+98}=\frac{z}{14y(x+7)}[/tex]
Using the cross product method, we get
[tex]3\times14y(x+7)=z(14x+98)[/tex]
[tex]42y(x+7)=z(14x+98)[/tex]
Dividing both sides by 14x+98, we get
[tex]\frac{42y\mleft(x+7\mright)}{14x+98}=\frac{z\mleft(14x+98\mright)}{14x+98}[/tex]
[tex]\frac{42y\mleft(x+7\mright)}{14(x+7)}=z[/tex]
[tex]\frac{42y}{14}=z[/tex]
[tex]3y=z[/tex]
Hence the answer is
[tex]\frac{3}{14x+98}=\frac{3y}{14y(x+7)}[/tex]
