Okay, so we know that Adam earns £200, plus 10% of (42*8) and 15% of (15*14)
To work out the payment for the magazines, you multiply 42 and 8, which gives 366 and find 10% of that, which is £36.60
To work out the payment for the books, you multiply 14 by 15, which gives 210 and find 15% of that, which is £31.50
Then add all the amounts together
£200+ £36.60+ £31.50= £268.10