If Rohan gives Mehak 10 stickers, they will have equal numbers. If instead Mehak gives Rohan 10 stickers, Rohan will have twice as many as Mehak. How many stickers does Mehak have?

50Correct answerYour answer60Correct answerYour answer70Correct answerYour answer120Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

Let Mehak have $m$ and Rohan $r$ . First condition: $r - 10 = m + 10$ , so $r = m + 20$ .
Second condition: $r + 10 = 2(m - 10)$ .
Substitute: $m + 30 = 2m - 20$ , so $m = 50$ (and Rohan has 70).
Check: after the second swap, Rohan has 80 and Mehak 40.

Worth noting

When one person gives 10 to the other, the gap between them changes by 20, not 10; using $r = m + 10$ is the usual slip. 70 is Rohan's count and 120 the total.

Concept: Two conditions about a transfer, turned into a pair of equations
Typical timeTypical: 70 s
Your timeYours: —

The rule this testsWord problems into equations

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Ten questions from Linear and Quadratic Equations, at your own pace.

If Rohan gives Mehak 10 stickers, they will have equal numbers. If instead Mehak gives Rohan 10 stickers, Rohan will have twice as many as Mehak. How many stickers does Mehak have?

Explanation