As a sales person at scrapbooks and treasures alyssa receives a monthly base pay plus commission on all that she sells she sells $400 worth of merchandise in one month shoes paid $388 if she sells $1000 worth of merchandise in one month she is paid $520 find alyssa salary when she sells $3300 worth of merchandise

Let 
x =  base pay per month
y = commission per $1 of sales

Then the monthly pay for selling $100 of merchandise is
P = x + 100y

In one month, Alyssa earned $388 for selling $400 worth of merchandise.
Therefore
x + 400y = 388           (1)

In another month, she earned $520 for selling $1000 worth of merchandise.
Therefore
x + 1000y = 520        (2)

Subtract (1) from (2).
x + 1000y - (x + 400y) = 520 - 388
600y = 132
y = 0.22
From (1), obtain
x = 388 - 400y = 388 - 400*0.22 = 300

When Alyssa sells $3300 worth of merchandise, she earns
300 +0.22*3300 = $1026

$1026