Question

Mr Teo gives his pupils some marbles. If each pupil gets 6 marbles,

Answer 1

Answer:  7 pupils

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Explanation:

p = number of pupils

If each student gets 6 marbles, then that accounts for 6p marbles so far. Unfortunately in this situation, we're short 12 marbles. That means we really have 6p-12 marbles.

On the other hand, if each student gets 4 marbles each, then that's 4p marbles so far. Then we add on 2 since we have a those extra. In this situation we have 4p+2 marbles.

The expressions 6p-12 and 4p+2 represent the same total marble count. Set them equal to one another and solve for p.

6p-12 = 4p+2

6p-4p = 2+12

2p = 14

p = 14/2

p = 7 is the number of pupils

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Optional Section:

If you want to know the number of marbles, then say either

6p-12 = 6*7-12 = 42-12 = 30

or

4p+2 = 4*7+2 = 28+2 = 30

Either way, we have 30 marbles.