Draw a graph showing the earnings per hour, for an output range of 0 — 400 units per hour if the worker is paid under the following wage systems:

a. Daywork at £4 per hour

b. Straight piecework at 2p per unit

c. Differential piecework at 2p per unit from 0 — 200 units, 2.5p per unit for 201 to 250 units, 2.75p per unit for 251 to 300 units and 3p per unit for all units above 301.