x = 3 the expression 2x + 3 9
Step — multiply
2 × 3 = 6
Step — add
6 + 3 = 9
Result
9
When x = 3:   2x + 3 = 2×3 + 3 = 6 + 3 = 9
Slide to change x. The letter is just a placeholder — drop a number in for it and the whole expression turns into one number. Watch the result follow your slider.