Answer:
Step-by-step explanation:
For sales of N copies at $90 each, 90N is added to Dale's base salary of $1800.
P = 90N +1800
__
For N=23, Dale's salary would be ...
P = 90(23) +1800 = 2070 +1800 = 3870
Dale's total pay for selling 23 copies would be $3870.