Q1.
So, we are left with 2 shaded parts, i.e., 6⁄7 – 4⁄7 = 2⁄7. Try doing this same exercise using the number line.
Answer
Mark the unit in sevenths. Go forward to 6⁄7, then jump back 4 sevenths.
Start at 6/7
Jump back 4 steps of 1/7: 6/7 → 5/7 → 4/7 → 3/7 → 2/7
So 6/7 − 4/7 = 2/7
Jump back 4 steps of 1/7: 6/7 → 5/7 → 4/7 → 3/7 → 2/7
So 6/7 − 4/7 = 2/7
The number line gives the same answer as the strip picture.
Why the denominator does not change: subtraction is “take away”. Taking 4 pieces of size 1⁄7 from 6 pieces of the same size leaves 2 pieces of size 1⁄7.