Texas Math Models

Try “number line” or “4.5D”

The rule · add or subtract the top

3/5 + 4/5 = 1 2/5 Grade 4

the bottom number names the PIECE, so it does not change addingsubtracting 35+45 3 fifths + 4 fifths = 7 fifths =75 more than a whole, so write it the other way 75=125 add the top numbers · keep the bottom 125−45 2 fifths cannot give away 4 fifths borrow the whole back as 5 fifths 125=55+25=75 75−45=35 subtract the top numbers · keep the bottom

How this one works

How

add or subtract the top numbers and keep the bottom number the same.

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The same problem, other ways