A heater is designed to operate with a power of \( 1000 \,\text{W} \) in a \( 100 \,\text{V} \) line. It is connected in combination with a resistance of \( 10\,\Omega \) and a resistance \( R \), to \( 100 \,\text{V} \) mains as shown in figure. For the heater to operate at \( 62.5 \,\text{W} \), the value of \( R \) should be ______ \( \Omega \).
