The triangle given has base 60 and height 45
The scale says "1 unit:5 meters" which means that each unit on the grid is 5 meters. We can divide each dimension of the given triangle by 5 so we figure out how many units we'll need for each dimension of the new smaller triangle (that is similar to the original)
60/5 = 12
45/5 = 9
The smaller triangle must have a base of 12 and a height of 9
See the diagram below.
The area of this new triangle is (base*height)/2 = (12*9)/2 = 108/2 = 54 square units.