She has 40 coins all made up of quarters and dimes, And when she counted them up she had $7.75 from them, how much of each did she have?

x = number of quarters = 25

y = number of dimes = 15

Step-by-step explanation:

Let

x = number of quarters

y = number of dimes

1 dime = $0.10

1 quarter = $0.25

x + y = 40 (1)

0.25x + 0.10y = 7.75 (2)

From (1)

x = 40 - y

Substitute x = 40 - y into (2)

0.25x + 0.10y = 7.75 (2)

0.25(40 - y) + 0.10y = 7.75

10 - 0.25y + 0.10y = 7.75

- 0.25y + 0.10y = 7.75 - 10

-0.15y = -2.25

y = -2.25/-0.15

y = 15

Substitute y = 15 into (1)

x + y = 40 (1)

x + 15 = 40

x = 40 - 15

x = 25

x = number of quarters = 25

y = number of dimes = 15

Total quarters = 25 × $0.25

= $6.25

Total dimes = 15 × $0.10

= $1.5

a

step-by-step explanation:

strong negative correlation

4.5%

step-by-step explanation: