Solve for $x$ in the equation $3 x - 5 = 16$ .

easy 1 mark Class 8 · Mathematics · Linear Equations in One Variable

Answer

x = 7

The correct answer is $x = 7$ — Divide both sides by $3$ to isolate $x$ : $3 x /3 = 21/3$ gives $x = 7$ .

Step-by-step solution

Add $5$ to both sides to eliminate the constant term: $3 x - 5 + 5 = 16 + 5$ gives $3 x = 21$ .
Divide both sides by $3$ to isolate $x$ : $3 x /3 = 21/3$ gives $x = 7$ .

Common mistake: Adding instead of subtracting the constant term on the wrong side

Concept tested: Solving a single linear equation