Answer with Step-by-step explanation:
Let there be d dimes and q quarters
A woman has 21 total coins in her pocket.
⇒ d+q=21 ------(1)
1 dime=$ 0.1
1 quarter=$ 0.25
The total value of her change is $3.90
⇒ 0.1d+0.25q=3.90
Multiplying both sides by 100,we get
10d+25q=390 --------(2)
(2)-10×(1)
10d+25q-10d-10q=390-210
15q=180
Dividing both sides by 15, we get
q=12
Putting value of q in (1),we get
d=9
Hence, Number of dimes=9
and number of quarters=12
Write the number of dimes, then the number of quarters separated by a comma.
9,12
Simplify to -30-35y=-30-5y
Move all ys to the right and move constants left, -30y= 0
Divide by -30
y=0
Answer: he got 30 of them correctly
Step-by-step explanation: because 30% of 100 is 30.
Think of the original amount as 100%
If we want 100% of something we multiply by 1
To get from 100% to 1, we divide the percentage by 100
Decrease 100% by 19%
100% - 19% = 81%
Then to get the multiplier, divide by 100
81% / 100 = 0.81
To decrease by 19%, multiply by 0.81
