Question 1124559
Let  d = number of dimes,  q = number of quarters <br>

(1) d+q = 20     (from the given quantity of coins)
(2) 10d + 25q = 380    (equation derived from description of value of coins, expressed in cents)

10*(1) ==>  10d+10q = 200
subtract (2) -10d - 25q = -380
                            -15q = -180
 
q = 180/15 = 12  —(from (1))—>  d = 8
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Ans:  There are 12 quarters and 8 dimes.
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Check:   25(12) + 10(8) = 300 + 80 = 380 cents = $3.80 (ok)