How do I set up the simultaneous equation from these numbers? Having three feeds is throwing me off. I believe the barley straw and alfalfa hay numbers are supposed to be combined but I have no clue how.

Feed Formulation Using Simultaneous Equations Spring 2022 Using simultaneous equations, balance a daily ration for a 1,400 lb lactating cow (1 month postpartum, 30 lb peak milk production) on the basis of NEm (Mcal/day) and CP. Use corn grain, rolled and a 40%/60% mix of barley straw and alfalfa hay (early bloom) as the ingredients. Calculate the amount of calcium and phosphorus supplied by this ration. The feed composition values are all on a dry matter basis. STEP 1 Feed Composition NEm, Mcal/1b* CP, % Ca, % P, % Corn grain, rolled 98 9 0.02 0.30 Barley straw 44 4 0.33 0.08 Alfalfa hay, sun- cured, early bloom 19 0.26 59 1.41 *NOTE: Be sure you convert Mcal/cwt (from the feed composition table) to Mcal/lb (here). Mcal/cwt is the same as Mcal/100 lb. So, divide it by 100 and you'll get Mcal/lb. STEP 2 Animal Requirements Daily DM, 1b NEm, Mcal/day 19.4 19.8 CP, lb/day P, lb/day Ca, lb/day .104 3.53 .068 *NOTE: Be sure you are using the Daily Nutrients per Animal. Do NOT use "Diet Nutrient Density. STEP 3: Set up the simultaneous equations: Feed Formulation Using Simultaneous Equations Spring 2022 Using simultaneous equations, balance a daily ration for a 1,400 lb lactating cow (1 month postpartum, 30 lb peak milk production) on the basis of NEm (Mcal/day) and CP. Use corn grain, rolled and a 40%/60% mix of barley straw and alfalfa hay (early bloom) as the ingredients. Calculate the amount of calcium and phosphorus supplied by this ration. The feed composition values are all on a dry matter basis. STEP 1 Feed Composition NEm, Mcal/1b* CP, % Ca, % P, % Corn grain, rolled 98 9 0.02 0.30 Barley straw 44 4 0.33 0.08 Alfalfa hay, sun- cured, early bloom 19 0.26 59 1.41 *NOTE: Be sure you convert Mcal/cwt (from the feed composition table) to Mcal/lb (here). Mcal/cwt is the same as Mcal/100 lb. So, divide it by 100 and you'll get Mcal/lb. STEP 2 Animal Requirements Daily DM, 1b NEm, Mcal/day 19.4 19.8 CP, lb/day P, lb/day Ca, lb/day .104 3.53 .068 *NOTE: Be sure you are using the Daily Nutrients per Animal. Do NOT use "Diet Nutrient Density. STEP 3: Set up the simultaneous equations