Question

There are 156, 208 and 260 students in

Answer 1

156 = 2·2·3·13
208 = 2·2·2·2·13
260 = 2·2·5·13 
      = 2·2·13
      = 52
their gcf is 52, in 156 there are three 52, in 208 there are four 52, and in 260 there are five 52. So that there are minimum of twelve buses needed to be hired.
answer: 12
:)