A double-blind, randomized clinical trial evaluates a new antihypertensive agent for the prevention of heart failure in patients with stage 1 hypertension. 1000 participants are assigned to the placebo group and 1000 to the active treatment group. Over a 5-year follow-up, 250 of the placebo group develop heart failure compared to 150 of the treatment group. Which of the following is the number needed to treat (NNT) to prevent one case of heart failure?