Under the same load, wire $A$ having length 5.0 m and cross section $2.5 \times 10^{-5} \mathrm{~m}^2$ stretches uniformly by the same amount as another wire $B$ of length 6.0 m and a cross section of $3.0 \times 10^{-5} \mathrm{~m}^2$ stretches. The ratio of the Young's modulus of wire $A$ to that of wire $B$ will be: