Answer:She sold 21 magazines on Thursday
Explanation:
Step 1
The Total price of magazine sold on Thursday, Friday and Saturday, she sold $66 .
if she sold $3 more on Thursday than she did on Friday and $6 more on Saturday than she did on Thursday. The expression of the sales can be given as
Let T represent Thursday
F represent Friday
S represent Saturday such that
T + F+ S= 66
T+ T-3 + T+6= 66
Step 2----- Solving
T+ T-3 + T+6= 66
3T - 3+ 6=66
3T+3= 66
3T= 66-3
3T=63
T= 63/3
T= 21
F= T-3= 21-3 =18
S = T+6 = 21+6= 27
She sold 21 magazines on Thursday, 18 on Friday and 27 on Saturday