If y = 3x and x = 4, then y =

## The reasoning This is **direct substitution** — one of the most fundamental operations in algebra. You're given two pieces of information: - y = 3x (y equals 3 times x) - x = 4 Simply replace x with 4 in the first equation: y = 3x y = 3(4) y = **12** That's it! When you see "substitute," think "swap in the value." ## Why the wrong options tempt you **Option A (7):** This catches students who *add* instead of multiply — doing 3 + 4 = 7. Always check the operation sign carefully! **Option C (1):** Maybe from confusing division? Or misreading the question entirely. **Option D (34):** This tricks students who just mash the numbers together as "34" instead of calculating 3 × 4. Don't concatenate — calculate! ## Quick takeaway **When you see y = 3x and are given x's value, multiply immediately — substitution means "plug it in and solve."** These questions test if you can follow simple instructions carefully, which JAMB loves to do!