Refer to figure.
We are given a chart to calculate the Landing Distance (LD) for a Class B MEP aeroplane. We are provided with the relevant meteorological conditions for the landing runway, as well as the LDA. For commercial operations, with a Class B aeroplane, we must be able to land within 70% of the LDA. That is, we apply a factor of 1.43 to our calculated LD to find the LDR. The max LDR we can use is equal to the available LDA = 2600 ft.

We must de-factor the LDR to enter the chart with our LD: 2600 x 0.7 = 1820 ft.
(This is equivalent to dividing by 1.43, but we avoid rounding error by using the 0.7. You can do this how you like in your exam, as the difference will only be a few feet.)

1. Enter the left side of the chart from 10°C, and draw a line vertically up to 2000 ft PA. Draw a line horizontally right to the Reference Line for Mass. It helps to also draw a new line from the reference line, to the end of the mass section of the chart as in the figure.
2. Enter the right side of the graph from 1820 ft. Follow parallel to the 50 ft obstacle lines, to the reference line. Follow horizontally to the left, until the 14 kt headwind mark, then follow the lines to the next (wind) reference line.
3. Draw a line horizontally from the wind reference line, and find where this crosses the weight line we drew. Draw a line vertically down from the crossover point: this is the maximum landing mass we can accept for the conditions and LDA (close to 3350 lbs).