Explanation:
part 1: 64/125 - 2/3
make the denominator ( bottom number) the same
x/125 and x/3
125×3 and 3×125
x/375 and x/375
whatever we do to the denominator we have to do to the numerator ( top number)
64/125
125 × 3
so
64 ×3
=64×3/125×3
=192/375
2/3
3 × 125
so
2 × 125
=2×125/3×125
=250/375
put together:
192/375 - 250/375
denominator is the same so we can simply take 192 from 250
192 - 250 = -58
= -58/375
part 2: + (256/625)-1/4
-58/375 + (256/625)-1/4
do the same for (256/625)-1/4 as in part 1
then add it to -58/375 by making the denominator the same
part 3: + (7/3)
make the denominator the same and add
part 4: simplify
divide a number from both the top and bottom till there is nothing you can divide from both