A brand of cereal had 1.2 milligrams iron per serving. Then they changed their recipe so they had 1.8 of iron per serving. What was the percent increase in iron?

Gabriel determined that his total cost would be represented by 2.5x + 2y – 2. his sister states that the expression should be x + x + 0.5x + y + y – 2. who is correct? explain.