Please help. I am struggling

Questions 29 through 31 use the following information: Consider a group of 1,000 newborn infants. One hundred (100) infants were born with serious birth defects, and 20 of these 100 died during the first year of life. Ninety (90) of the 900 remaining infants without any birth defects also died during the first year of life. Calculate the prevalence of serious defects in this population at the time of birth. (a)/(b)=(c) Formatting you answer: DO NOT enter ANYTHING except the final numbers you arrive to for your numerators, denominators, and percent answer. This means I do not need to see your numerator math, for example, your conversion from decimal to percent, or any parentheses. This question auto-grades based on the expected format of your answer. . numerator=a denominator=b percentage=c QUESTION 30 Calculate the overall cumulative incidence of mortality in this population. (a)/(b)=(c) Formatting you answer: DO NOT enter ANYTHING except the final numbers you arrive to for your numerators, denominators, and percent answer. This means I do not need to see your numerator math, for example, your conversion from decimal to percent, or any parentheses. This question auto-grades based on the expected format of your answer. numerator=a denominator=b percentage=c QUESTION 31 Calculate the risk difference (or attributable risk) in mortality between infants born with serious birth defects and without. (a)-(b)=(c) Formatting you answer: DO NOT enter ANYTHING except the final numbers you arrive to for your numerators, denominators, and percent answer. This means I do not need to see your numerator math, for example, your conversion from decimal to percent, or any parentheses. This question auto-grades based on the expected format of your answer. numerator=a denominator=b percentage=