Here, triple point of water on scale, $A = 200 A$triple point of water on scale $B = 350 B$triple point of water on kelvin scale $= 273.16\,\mathrm{K}$According to question, $200 A = 350 B = 273.16\,\mathrm{K}$ $1 A = \frac{273.16}{200} \mathrm{K},$$1 B = \frac{273.16}{350} \mathrm{K}$If $T_A$ and $T_B$ represent the triple point of water on two scales A and B, then$\frac{273.16}{200} T_A = \frac{273.16}{350} T_B,$$\frac{T_A}{T_B} = \frac{200}{350} = \frac{4}{7},$$T_A = \frac{4}{7} T_B$