29
Note that consecutive numbers have a difference of 1 between them.
let n be the smallest integer then the three integers can be expressed as
n, n + 1 , n + 2
the sum is then
n + n + 1 + n + 2 = 90
3n + 3 = 90
subtract 3 from both sides of the equation
3n = 90 - 3 = 87
divide both sides by 3
n = = 29
the three integers are 29, 30, 31 → the smallest is 29