28+112−k=175\sqrt{28} + \sqrt{112} - \sqrt{k} = \sqrt{175}28+112−k=175
4×7+16×7−k=25×7\sqrt{4 \times 7} + \sqrt{16 \times 7} - \sqrt{k} = \sqrt{25 \times 7}4×7+16×7−k=25×7
27+47−k=572\sqrt{7} + 4\sqrt{7} - \sqrt{k} = 5\sqrt{7}27+47−k=57
67−57=k6\sqrt{7} - 5\sqrt{7} = \sqrt{k}67−57=k
k=7\sqrt{k} = \sqrt{7}k=7
⟹ k=7\implies k = 7⟹k=7
