Problems based on Numbers Test 1

Let the number be 10x + y then
10x + y = 3 (x + y)
⇒ 7x – 2y = 0 ...(i)
Also, 10x + y + 45 = 10y + x
⇒ 9x – 9y = – 45
⇒ x – y = – 5 ...(ii)
Solving equations (i) and (ii) we get, x = 2 and y = 7
Hence, number = 10 × 2 + 7 = 27