Let x is the fixed charge and y is the variable charge per word. We have
x + 5y = 3 …..(i)
x + 10y = 4.25 …….(ii)
(ii) – (i) ⇒ 5y = 1.25 ⇒ y = 0.25. Put this value in (i), we get
x + 1.25 = 3 ⇒ x = 1.75
Now the cost to send a 35 word telegram = x + 35y = 1.75 + 35 × 0.25 = 1.75 + 8.75 = Rs 10.50