Instead of doing your problems for you, I'll change only the numbers and work
problems exactly like yours step by step, that you can use as models to solve
your problems by.  Notice that the numbers are different but they are worked
exactly the same way:

q = number of quarters 
$0.25q = value of all the quarters
q+17 = number of pennies   <-- the more...than... tells us to ADD q and 17.
$0.01(q+17) = value of all the pennies



$0.25q + $0.01(q+17) = $2.51
   25q +     1(q+17) =   251
       25q + 1q + 17 = 251
            26q + 17 = 251
Subtract 17 from both sides
                 26q = 234
Divide both sides by 26
                   q = 9     <-- So Chris has 9 quarters   

q+17 = number of pennies = 9+17 = 26 <-- So Chris has 26 pennies

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d = number of dimes 
$0.10d = value of all the dimes
11∙d = number of nickels    <--the word "times" tells us to multiply 11 by d.
$0.05(11∙d) = value of all the nickels



$0.10d + $0.05(11∙d) = $3.90
   10d +     5( 11d) =   390
           10d + 55d = 390
                 65d = 390
Divide both sides by 65
                   d = 6     <-- So Chris has 6 dimes   

11∙d = number of nickels = 11∙6 = 66 <-- So Tiana has 66 nickels

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q = number of quarters 
$0.25q = value of all the quarters
3q+8 = number of nickels  <--the "more than three times" tells us to ADD 3q and  7.
$0.05(3q+8) = value of all the nickels



$0.25q + $0.05(3q+8) = $2.40
   25q +     5(3q+8) =   240
      25q + 15q + 40 = 240
            40q + 40 = 240
Subtract 40 from both sides
                 40q = 240
Divide both sides by 35
                   q = 5     <-- So Kelsey has 5 quarters   

3q+8 = number of nickels = 3(5)+8 = 15+8 = 23 <-- So Kelsey has 23 nickels

Edwin