If a 1lıtre can of paınt ıs enough to cover 5m of wall area,and then can cost R26,00 how much wıll ıt cost to buy the paınt for paıntıng these two sıdes of house?

can't say, since you don't say how big the sides are. Also, I assume you mean that 1 litre covers 5m^2 of area.

In any case, figure the area to be painted, in m^2, and then multiply that by R26/5m^2