The given equation is
v = u + at
To make a subject we have to isolate it on a side and put the others on the other side
To do that we will subtract u from each side
v - u = u - u + at
v - u = at
Now, we will divide each term by t
[tex]\frac{v-u}{t}=a[/tex]Switch the 2 sides
[tex]a=\frac{v-u}{t}[/tex]