x 3 x + 3 = 8 Come play with numbers!
Word problems

Where is x hiding in money and age?

# Age and money stories ## Money “I have ₹x. I spend ₹15 and have ₹40 left.” `x − 15 = 40` → `x = 55` ## Age “Riya is x years old. In 4 years she will be 15.” `x + 4 = 15` → `x = 11` ## Two items “A pen is ₹x. A book costs ₹20 more. Together they cost ₹70.” `x + (x + 20) = 70` `2x + 20 = 70` `2x = 50` `x = 25` Book = 45. Check: 25 + 45 = 70 ✓ > After you find x, **name what it is** in a sentence: “The pen costs ₹25.” ## Two extra skills for stories ### 1. Name the second thing in terms of the first If the pen is x and the book is ₹20 more, do not invent a second mystery y unless you need it. Write `x + 20`. ### 2. Answer in a sentence Algebra teachers and exam papers ask for meaning. Not only: `x = 25` Also: **The pen costs ₹25. The book costs ₹45.** ### Together means add “Together they cost 70” → (first) + (second) = 70. That one sentence is how almost every two-item money problem starts.

By the end of this lesson

Set up and solve age and money stories, including “₹20 more” as (x + 20), then name the answer in a sentence.

Remember

  • Money left: start − spend = left. x − 15 = 40 → x = 55.
  • Age in the future: now + years = then. x + 4 = 15 → x = 11.
  • “₹20 more than the pen” is x + 20 if the pen is x.
  • Together: add the two expressions, set equal to the total.
  • After you find x, write a sentence: “The pen costs ₹25.”

Worked examples

Cover the answer. Try the steps on paper, then open them.

Example 1 — Pocket money

I had ₹x, spent ₹15, have ₹40 left.

  1. x − 15 = 40
  2. x = 55
  3. Sentence: I started with ₹55.
  4. Check: 55 − 15 = 40 ✓

Answer: ₹55

Example 2 — Birthday

Riya is x years old. In 4 years she will be 15.

  1. x + 4 = 15
  2. x = 11
  3. Riya is 11 now.
  4. 11 + 4 = 15 ✓

Answer: 11 years

Example 3 — Pen and book

Pen ₹x, book ₹20 more, together ₹70.

  1. Book = x + 20
  2. x + (x + 20) = 70
  3. 2x + 20 = 70
  4. 2x = 50
  5. x = 25
  6. Book = 45. Check: 25 + 45 = 70 ✓

Answer: pen ₹25, book ₹45

Common mistakes

Slip Writing “book is 20 more” as 20x.

Fix 20 more is +20, not times 20.

More → add.

Slip Stopping at x = 25 and not finding the book.

Fix The question often wants both.

x + 20 = 45.

Slip x − 15 = 40 → x = 25.

Fix Undo minus by adding: 40 + 15 = 55.

You started with more than you have left.

Try on paper first

Write the answer, then tap Reveal. These are not the quiz — they are warm-ups.

1. x − 20 = 30 → I started with ₹…

Answer: 50

2. x + 6 = 17 → age now is…

Answer: 11

3. x + (x + 10) = 50 → x =

Answer: 20

4. If x = 20 and the other item is 10 more, the other is…

Answer: 30

Touch practice

9 tap / type

Tap an option or type the answer. Retry any miss. Extra generated questions appear after the set if this topic allows it.

Optional picture lab

After practice

Real world

Pocket money and birthdays.

Connect

Business logic in apps.

⭐ Star quiz

9 questions

Finish the touch practice first if you can. Then answer without peeking. Read every “why”.

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