Factor $20=2^{2}\times 5$. Rewrite the square root of the product $\sqrt{2^{2}\times 5}$ as the product of square roots $\sqrt{2^{2}}\sqrt{5}$. Take the square root of $2^{2}$.
$$15\times 2\sqrt{5}+7\sqrt{45}-2\sqrt{125}$$
Multiply $15$ and $2$ to get $30$.
$$30\sqrt{5}+7\sqrt{45}-2\sqrt{125}$$
Factor $45=3^{2}\times 5$. Rewrite the square root of the product $\sqrt{3^{2}\times 5}$ as the product of square roots $\sqrt{3^{2}}\sqrt{5}$. Take the square root of $3^{2}$.
$$30\sqrt{5}+7\times 3\sqrt{5}-2\sqrt{125}$$
Multiply $7$ and $3$ to get $21$.
$$30\sqrt{5}+21\sqrt{5}-2\sqrt{125}$$
Combine $30\sqrt{5}$ and $21\sqrt{5}$ to get $51\sqrt{5}$.
$$51\sqrt{5}-2\sqrt{125}$$
Factor $125=5^{2}\times 5$. Rewrite the square root of the product $\sqrt{5^{2}\times 5}$ as the product of square roots $\sqrt{5^{2}}\sqrt{5}$. Take the square root of $5^{2}$.
$$51\sqrt{5}-2\times 5\sqrt{5}$$
Multiply $-2$ and $5$ to get $-10$.
$$51\sqrt{5}-10\sqrt{5}$$
Combine $51\sqrt{5}$ and $-10\sqrt{5}$ to get $41\sqrt{5}$.
