Question

Evaluate the problem
5/8 - 1/4.

Answer 1

3/8

Explanation:

5/8 - 1/4

to be able to compare fractions or add/subtract them directly, we need to bring them all to the same denominator (the bottom part of the fractions).

it is usually easier to bring the smaller to a larger number than the other way around, because of the existing numerators (the top part of a fraction).

since we are dealing with fractions (divisions !), the best way to manipulate them is by multiplying or dividing them by a factor.

so, what do we need to multiply with 4 to get 8 (the other denominator) ?

2, as 4×2 = 8.

aha.

but now careful, we cannot just multiply the denominator by 2. that would change the value of the whole original fraction.

we have to multiply denominator AND numerator by the same factor. that way the original value of the fraction remains the same, because we are essentially multiplying the whole fraction just by 1.

so,

1/4 × 2/2 = 2/8

and now we can easily use it in a calculation with other 8ths :

5/8 - 2/8 = 3/8

Answer 2

5/8 - 1/4 = 3/8

Explanation:

• Convert to equivalent fractions by multiplying the top and bottom of 1/4 by 2, in order to match 5/8's denominator.

1 x 2 = 2, 4 x 2 = 8, so we're left with 2/8

• subtract as normal, top by top.
• 5 - 2 = 3.
• therefore 5/8 - 1/4 = 3/8