A band of cereal had 1.2 milligrams (mg) of iron per serving. Then they changed their recipe so they had 1.8 mg of iron per serving

50%

Step-by-step explanation:

1 - get the difference between the two numbers:

difference = 1.8 - 1.2 = 0.6 mg

2 - divide the difference by the original number and then multiply the quotient by 100 to get the percentage

% of increase = (0.6/1.2) * 100 = 50%