How do you simultaneous equations? fir example 5a + 2b = 14. we did it in lesson and i just blanked out xd

First of all, 'simultaneous' equations means more than one equation. 
You have a set of them, with as many equations as there are variables
in them.

Here you wrote  ' 5a + 2b = 14 '.

You can't do anything with this single equation, except maybe graph it
and get a straight line.  If you want to find the values of 'a' and 'b', you
need another equation with 'a' and 'b' in it, and the two equations together
are called 'simultaneous' because they're both true at the same time.

If you graphed both of them, you would find that each equation makes a
different straight line.  The lines cross at one point, and the (a,b) at that
point is the solution of the simultaneous equations. But there are other
ways to solve the pair of equations without graphing them. Those are
the ways to 'do' them that were probably being discussed in class. 

If you post a pair of simultaneous equations here on the site, somebody
is sure to solve it for you.  And if you get really lucky, they may even explain
how they did it.

Dwould be the answer