Suzy has a collection of quarters and dimes. Together she has 34 coins worth $6.40. How many quarters and how many dimes does Suzy have? Please show your work :)

Quarters = 20

Dimes = 14

Step-by-step explanation:

Dime = x = 10 cent = $0.1

Quarter = y = 25 cent = $0.25

x + y = 34 - - - (1)

0.1x + 0.25y = 6.40 - - - - (2)

From (1)

x = 34 - y

0.1(34 - y) + 0.25y = 6.40

3.4 - 0.1y + 0.25y = 6.40

3.4 + 0.15y = 6.40

0.15y = 6.40 - 3.40

0.15y = 3

y = 3 / 0.15

y = 20

x = 34 - y

x = 34 - 20

x = 14

Quarters = 20

Dimes = 14

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value