n + 9n - 90 = 0 Solve for n in the equation n + 9n - 90 = 0 Step 1: Group the n terms on the left hand side: (1 + 9)n = 10n Step 2: Form modified equation 10n - 90 = Step 3: Group constants: We need to group our constants -90 and 0. To do that, we add 90 to both sides 10n - 90 + 90 = 0 + 90 Step 4: Cancel 90 on the left side: 10n = 90 Step 5: Divide each side of the equation by 10 10n/10 = 90/10 n = 9