Some of students went on atrip. They could be split into groups of 7 of 6 but if they were split into groups of 5 then one is a student short how many went

Question

we Are learning about factors and multiples

Answer 1

5x + 4 = 9, or 14, or 19, or 24, or 29, or 34, or 39, or 44, or 49, or 54, or 59, or 64, or 69. or 74, or 79, or 84...  Hey!  84 is divisible by 6 and by 7 evenly.  So there must have been 84 students...