\(y=\frac{50^{15}.13^{18}}{25^7.26^{15}.5^{16}}=\frac{\left(2.5\right)^{15}.13^{18}}{\left(5^2\right)^7.\left(2.13\right)^{15}.5^{16}}=\frac{2^{15}.5^{15}.13^{18}}{5^{14}.5^{16}.2^{15}.13^{15}}=\frac{2^{15}.5^{15}.13^{18}}{5^{30}.2^{15}.13^{15}}=\frac{13^3}{15^{15}}\)