<LMP and <NMP are supplementary angles so sum = 180
<LMP + <NMP = 180
(-16x + 13) + ( - 20x + 23) = 180
-16x + 13 - 20x + 23 = 180
-36x + 36 = 180
-36x = 144
x = -4
<LMP = -16x + 13 = -16(-4) + 13 = 77
<NMP = - 20x + 23 = - 20(-4) + 23 = 103
Answer
<LMP = 77°
<NMP = 103°
A is false but R is true (the mean of the last 3 values is not 8 since x=7)
So first you would divide 1950/6 to find the amount for one year of their age.
Then you would multiply that by the ages, which should get you 4 numbers, then you all those numbers together. Try 9750.