Answer:
15
Step-by-step explanation:
(18+22+17+x)/4=18
18+22+17+x=18×4
57+x=72
x=72-57
x=15
Answer: 4 x − 7 = 2 4x-7=2 4x−7=2. Add 7 to both sides. Simplify 2 + 7 2+7 2+7 to 9. Divide both sides by 4.
Step-by-step explanation:
The complete table will be:

<u><em>Explanation</em></u>
Suppose, the number of sit-ups in Sunday is 
Mean is the simple average of some numbers. <u>For finding the mean number</u> of sit-ups per day, we need to <u>divide the 'total number of sit-ups' by the 'total number of days'</u>.
Here the total number of days is 7 and the total number of sit-ups for 7 days 
Given that, the mean number of sit-ups per day is 100. So, the equation will be...

So, the number of sit-ups you have to do Sunday is 175.
FGHI
Step-by-step explanation:
The square FGHI needs to be created into a reflection for true congruence of the figure thus transformed across the axis.
FGHI's co-ordinates' signs are to be reversed for reflection thus coordinates:
2,-5
4,-5
2,-7
4,-7
are made into
-2,5
-4,5
-2,7
-4,7