Find the altitude of triangle and then find the total area?

How about using the Pythagores theorem?

Use the perimeter to find the width and then work on the area of rectangle times by cost of gardening.

First find the altitude of trapezium by the using the concept of centroid that divides height in 2:1 and then find the area of the trapezium.

First find the area of a tile and then divide the area of square by area of tile.

Area of triangle = (h x b) /2

First, find the missing side of trapezium by finding the perimeter of the square and then find the height of trapezium by Pythagoras theorem.