Only two problems I don’t understand. Don’t just give me answer, explain too please.

12. Option b: 20 is the correct answer.

13. Option a: A rose costs $1 more than a daisy is the correct answer.

Step-by-step explanation:

12. Given that:

15x+10y=700       Eqn 1

x+y=60      Eqn 2

To find x, we will eliminate y be multiplying Eqn 2 by 10

10(x+y=60)

10x+10y=600      Eqn 3

Subtracting Eqn 3 from Eqn 2

(15x+10y)-(10x+10y)=700-600

15x+10y-10x-10y=100

5x=100

Dividing both sides by 5

Hence,

Option b: 20 is the correct answer.

13. Given that:

5x+4y=32     Eqn 1

x+6y=22       Eqn 2

Multiplying Eqn 2 by 5

5(x+6y=22)

5x+30y=110     Eqn 3

Subtracting Eqn 1 from Eqn 3

(5x+30y)-(5x+4y)=110-32

5x+30y-5x+4y=78

26y=78

Dividing both sides by 26

Putting y=3 in Eqn 2

x+6(3)=22

x+18=22

x=22-18

x=4

Hence,

Option a: A rose costs $1 more than a daisy is the correct answer.