Let x be the number of nickels and y be the number of quarters.
Then, x + y = 42 --- (1)
It is given that total value = 4.90.
Therefore, 0.05x + 0.25y = 4.9 --- (2)
Multiply (1) by 0.25
0.25x + 0.25y = 10.5 --- (3)
Now, subtract (2) from (3), we get,
0.2x = 5.6
Divide both sides by 0.2.
x = 28
x + y = 42
y = 42 - x
= 42 - 28
= 14
Hence, Mary has 28 nickels and 14 quarters in total.
So 30 and 2.5 would be subtracted and added by whatever value. Then divided hope that helped
Answer:

Step-by-step explanation:
Given
Cost of Textbooks ---- Frequency
$25 up to $35 ----- 2
$35 up to $45 ------- 5
$45 up to $55 ------- 7
$55 up to $65 ------ 20
$65 up to $75 ---- -- 16
Required
Determine the relative class frequency for the $25 up to $35 class
First, we need to get the total frequency


Next, is to write out the frequency of $25 up to $35 class

Divide this frequency by the total frequency; This gives the relative frequency



Hence;
Option D answers the question
9:20 am
Lcm is 80 so 80 minutes after 8 am is 9:20
P=2L+2W
P-2W=2L
P/2-W=L
L=P/2-W