From a puzzle to a line
A cycle shop charges ₹15 for each patch. A patch is a rubber piece that seals a hole. Fitting the tube costs ₹25. The bill is ₹85. How many patches? Call that number p.
Loading lab…
Step 1 of 4
- ₹15 a patch, ₹25 to fit.
- Repeats:
15p. Once:25. 15p + 25 = 85- Solve:
p = 4.
Two amounts, two jobs
The bill is for 4 patches. Check: 15 × 4 + 25 = 85.
Which amount repeats for each patch? The ₹15. So it goes with the letter: 15p. That means 15 times p.
What happens once for the whole job? The ₹25 fitting charge. It stands alone.
Together: 15p + 25 = 85. Take 25 off both sides: 15p = 60, because 85 − 25 = 60. Share both sides by 15: p = 4, because 60 ÷ 15 = 4.
Rule: The amount that repeats goes with the letter. The amount charged once stands alone.