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I've set out suvat and tried to find an equation for the different heights but I am totally lost.

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    What equation did you try to write? Even if it is wrong, the more things you show you did, the better. – 2017-01-11
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    @RSerrao i tried using the "s = ut + 1/2at^2" formula to find t – 2017-01-11
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    What hapenned with the s.u.v.a.t equations? $s=ut + at^2/2$ not do it? – 2017-01-11
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    @Bacon the question is to find an expression for the heights separating the troopers. – 2017-01-11
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    @Rumplestillskin for paratrooper 1 I got s = -4.9(t) and paratrooper 2 was s = -4.9(t+2). After that I had no clue what to do... – 2017-01-11
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    You're supposed to find $s_1-s_2$ expressed in $t$. You have the expressions for $s_1$ and for $s_2$ in your comment just there, so you are quite close. However, note that for the second paratrooper it's $(t-2)$, not $(t+2)$. – 2017-01-11
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    Get an equation for $s_1$ And $s_2$ for both troopers. One with time $t$ the other with time $t+2$. Then subtract them. The acceleration is $-g$ due to gravity. – 2017-01-11
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    @Arthur why do you think it's $t-2$? – 2017-01-11
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    @Rumplestillskin Because at $t=2$, he is at the origin. Now just insert and check that this means you need his time component in the formula to be $t-2$. – 2017-01-11

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Let
$\qquad y_1(t)$=vertical distance of first paratrooper from helicopter, and
$\qquad y_2(t)$=vertical distance of second paratrooper from helicopter.

Difference in height between paratroopers at time $t \;(>2)$ is $$y_1(t)-y_2(t)=\frac 12 g(t+2)^2-\frac 12 gt^2=\color{red}{2g(t+1)}$$

Distance of first paratrooper as observed by second paratrooper increases linearly with time.