Let the present age of the man and his wife be $4x$ and $3x$ respectively.

After $4$ years this ratio will become $9:7$

$\Rightarrow (4x+4):(3x+4)=9:7$

$\Rightarrow 7(4x+4)=9(3x+4)$

$\Rightarrow 28x+28=27x+36$

$\Rightarrow x=8$

The present age of the man $=4x=>>4\times 8=32$
The present age of his wife $=3x=>>3\times 8=24$

Assume that they got married before  years. Then,

$\Rightarrow$

$\Rightarrow 3(32-t)=5(24-t)$

$\Rightarrow 96-3t=120-5t$

$\Rightarrow 2t=24$

$\Rightarrow t=\frac{\mathrm{24/}}{2}=12$