Microsoft PowerBi & DAX

I am in need of some help with Microsoft PowerBi & DAX. I have data which includes Month to Date sales and Monthly Targets. I am trying to identify the best way to calculate End of Month Projected Sales & End of Month Projected Attainment. Example: It is the 18th of October and I currently have 50 Actual Items sold Month To Date. My Target/Goal for the month is to sell 85 Items. Based on these numbers, I am projected to sell 86.1 items in the Month of October with an attainment of 101.3%. For projected Sales (Calculation: (50 Items/18 Days) * 31 Days = 86.1), For Projected Attainment (Calculation: 86.1 Projected Sales /85 Target Sales = 1.013 or 101.3%). While I could use real numbers, they are obviously variable and I would need to to change when the data changes each day.