A) to find the difference you have to subtract one from the other (53-(-41)=91)
b) 15
<span>The inner core is made of solid iron, and it is surrounded by the liquid iron of the outer core. It is solid because the extreme pressure at the center of the earth prevents it from melting, despite the unimaginable temperatures.</span>
First find the amount of each payment:

The total cost will be 40 payments plus service charges.

The percentage is the service charge divided by total cost:
Let P = number of coins of pennies (1 penny = 1 cent)
Let N = number of coins of nickels (1 nickel = 5 cents)
Let D = number of coins of dimes (1 dime = 10 cents)
Let Q = number of coins of quarters (1 quarter = 25 cents)
a) P + N + D + Q = 284 coins, but P = 173 coins, then:
173 + N + D + Q =284 coins
(1) N + D + Q = 111 coins
b) D = N + 5 OR D - N =5 coins
(2) D - N = 5 coins
c) Let's find the VALUE in CENTS of (1) that is N + D + Q = 111 coins
5N + 10D + 25 Q = 2,278 - 173 (1 PENNY)
(3) 5N + 10D + 25Q = 2105 cents
Now we have 3 equation with 3 variables:
(1) N + D + Q = 111 coins
(2) D - N = 5 coins
(3) 5N + 10D + 25Q = 2105 cents
Solving it gives:
17 coins N ( x 5 = 85 cents)
22 coins D ( x 10 = 220 cents)
72 coins D ( x 25 = 1,800 cents)
and 173 P,
proof:
that makes a total of 85+2201800+172 =2,278 c or $22.78
I hope this helps.if you have any questions regarding what I did you can ask