A florist had an equal number of red and yellow tulips. She sold 624 red tulips. Then she had 4 times as many yellow tulips as red tulips. How many tulips did she start with? You must use a bar model to solve this problem.
after the sale, she had
r-624 red and r yellows, so
r = 4(r-624)
3r = 2496
r = 832
check: 832-624 = 208
832 = 4*208