The sum of two consecutive interferes is at least 7 (n and n + 1 represent two interferes

Consecutive integers are 1 apart so they are n and n+1

their sum (add) is at least 7

sum>7

sum means add

n+n+1>7

2n+1>7

minus 7 both sides

2n>6

divide 2

n>3

the smaller number mist be at least 3, (making the bigger number at least 4)