Answer :
(1/2)*x - (3/10)*x = 200
(5/10)*x - (3/10)*x = 200
(2/10)*x = 200
(1/5)*x = 200
x = 200*(5/1)
x = 200*5
x = 1,000 pennies
(5/10)*x - (3/10)*x = 200
(2/10)*x = 200
(1/5)*x = 200
x = 200*(5/1)
x = 200*5
x = 1,000 pennies