Can someone me to find the answer of this question? i don't really understand how to calculate the numbers.

Use this data in the problem below. follow the steps carefully. round to the nearest tenth. lot 3: week 1: 345 week 2: 340 week 3: 400 week 4: 325 step 1. jim enters the data and calculates the average or mean. step 2. jim calculates the deviation from the mean by subtracting the mean from each value. step 3. jim squares each deviation to remove negative signs. step 4. jim sums the squares of each deviation and divides by the count for the variance. step 5. jim takes the square root of the variance to find the standard deviation.

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

The measure of an angle is 117°. what is the measure of a supplementary angle?