Luis has a change jar that contains only pennies and dimes. he has 74 coins which add up to a total of $4.61. how many of each type of coin does he have?

p + d = 74 coins

rewrite as p = 74-d

0.01p + 0.10d = 4.61

0.01 (74-d) + 0.10d = 4.61

0.74 - 0.01d + 0.10d = 4.61

0.74 + 0.09d = 4.61

0.09d = 3.87

d = 3.87/.09 = 43

p = 74-43 = 31

43 dimes and 31 pennies