Question

Tick (✓) the correct answer
If 4xy7 is exactly divisible by 3, then the least value of (x + y) is
(a) 1
(b) 4
(c) 5
(d) 7

Answer 1

(a) 1
If a number is divisible by 3, the sum of the digits is also divisible by 3.
$4+x+y+7=11+(x+y)$
For the sum to be divisible by 3:
$11+(x+y)=12\Rightarrow (x+y)=1$