Twenty-five less than three times a number is at least 26

3 times a number is written as 3x (where x is the number).

25 less than that becomes 3x-25

then it is at least 26, which means it is at least 26 or bigger

3x-25 ≥ 26

Now solve for x:

Add 25 to each side:

3x ≥26 + 25

3x ≥ 51

Divide both sides by 3:

x ≥51 / 3

x ≥ 17