Tina bought 9 non-fiction books of the same kind during the Lunar New Year Sale. Jean bought 3 of the same non-fiction books. Jean also bought 2 coins at $2.30 each. Altogether, she spent $1.60 more than Tina. What was the amount Jean spent?
Amount that Jean spent on 2 coins
= 2 x 2.30
= $4.60

Let the cost of each non-fiction book be 1 u. 

Amount that Tina spent = 9 u

Amount that Jean spent =  3 u + 4.60

Jean spent $1.60 more than Tina.  If Tina spent another $1.60, she would spend the same amount as Jean.

9 u + 1.60 = 3 u + 4.60
9 u - 3 u = 4.60 - 1.60
6 u = 3.00

1 u = 3.00 ÷ 6 = 0.50

Cost of each non-fiction book
= 1 u
= $0.50

Amount that Jean spent
= 3 x 0.50 + 4.60
= 1.50 + 4.60
= $6.10

Answer(s): $6.10