Verified answer

Let the total sales be x.

A salesman gets a basic wage of £80 per week plus a commission of 30% of the sales he makes in that week

Weekly wages = 80 + 0.30x

In one week his total wage was £800

80 + 0.3x = 800

0.3x = 720

x = 2400

He made total sales of £2400 that week.

800 = .30x + 80

720 = .30x

2400 = x

He made 2400 sales that week.