Question 151623
Equivalent fractions: These are fractions that have exactly the same value but are different in appearance.
For example: {{{1/2}}} and {{{5/10}}} are equivalent fractions. 
To show this, you can take the {{{5/10}}} and write the numerator (top) and the denominator (bottom) in terms of their factors, thus:
{{{5/10 = (1*5)/(2*5)}}} Now if you cancel the 5 in the top with the 5 in the bottom, you are left with:
{{{(1*cross(5))/(2*cross(5)) = 1/2}}}
So...{{{1/2}}} and {{{5/10}}} are equivalent fractions.
Now back to your son's problem:
The first fraction is {{{3/4}}} 
To write an equivalent fraction, you simply can multiply the numerator and the denominator by the same number, say 2, for instance, thus:
{{{3/4 = (2*3)/(2*4)}}} = {{{6/8}}}
So, {{{3/4}}} and {{{6/8}}} are equaivalent fractions.
To get the second equaivalent fraction, you can multiply the numerator and the denominator by 3:
{{{3/4 = (3*3)/(3*4)}}}={{{9/12}}}
So {{{3/4}}}, {{{6/8}}}, and {{{9/12}}} are equivalent fractions.
You can follow this pattern for all the fractions on the list.
{{{7/9 = (2*7)/(2*9)}}} = {{{14/18}}} and...
{{{7/9 = (3*7)/(3*9)}}} = {{{21/27}}}
Do you see the idea?