Explanation:
For the expression (s-t)(s/t) we first use the distributive property:
[tex] (s-t)(\frac{s}{t})
\\
\\=s\times \frac{s}{t}-t\times \frac{s}{t} [/tex]
We can write both s and t as fractions by using a denominator of 1:
[tex] \\=\frac{s}{1}\times \frac{s}{t}-\frac{t}{1}\times \frac{s}{t} [/tex]
To multiply frations, we multiply straight across:
[tex] =\frac{s\times s}{1\times t}-\frac{t\times s}{1\times t}
\\
\\=\frac{s^2}{t}-\frac{ts}{t} [/tex]
In the second fraction, st/t, the t will divide out, or cancel, since it is in both the numerator and denominator:
[tex] \frac{s^2}{t}-s [/tex]
