Question 644542
Hint:


"You have 32 coins" ----> d+q = 32 which becomes d = 32 - q



"...that equals $6.20" ----> 0.1d + 0.25q = 6.20 which becomes 10d + 25q = 620


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Now plug d = 32 - q into the last equation


10d + 25q = 620


10(32 - q) + 25q = 620


and solve for q. Then use this solution to find d.