Solving a simple linear equation
The total is also 5 times r, one r in each pack. So 5 r and 75 are the same amount. So r is 75 divided by 5, which is 15.
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Transcript
A shop sells balloons in packs of R. A class buys 5 such packs, uses 12 balloons to decorate the hall, and has 63 balloons left. How many balloons are in each pack? Try it first. Pause if you like. The 63 balloons left are one blue strip. The 12 used came off the packs, so land them back on in purple. Now cut the whole strip into 5 equal packs. Together, 63 plus 12 is 75. The total is also 5 times r, one r in each pack. So 5 r and 75 are the same amount. So r is 75 divided by 5, which is 15. So each pack has 15 balloons.