Take a two-step equation like 3x + 4 = 19. Solving is two moves; verifying is one more. Three lines of working and you're certain.
Stage One — Solve
Undo the + or −. Take 4 off both sides: 3x = 19 − 4 = 15.
Undo the ×. Divide both sides by 3: x = 15 ÷ 3 = 5. There's your answer.
Stage Two — Verify
Don't stop there. Take x = 5 and slot it back into the original equation, left side only: 3×5 + 4 = 15 + 4 = 19. The right side is also 19. Both sides land on 19, so the answer is verified. Tick it and move on with full confidence.
Show Your Working Both Ways
In an exam, that little check line does two jobs: it catches your own slips, and it shows the marker you understand what a solution is. Use the toy to drill the rhythm — solve in your head or on paper, then hit "show me the steps" and watch the substitution check confirm it. Do a dozen and it stops feeling like extra work.