Different questions about Equations

Hi, this might be really simple, but I just don't get it, so I'd like some help ^^

Question 1:

'Part of a garden consist of a square lawn with a path 1.5 metres wide around its perimeter. If the lawn area is two-thirds of the total area, find the lenght of a side of the lawn.'

Question 2:

Solve the simultanious equations:

xy= 42

x - 4y = 17

Question 3:

Solve the equation:

(I don't know how to write fractions, but it's fractions..)

1/x + 2 **+** 1/ x^2 - 4 **=** 2/5

Help is very appreciated. ^^