Answer:
The mean age of the frequency distribution for the ages of the residents of a town is 43 years.
Step-by-step explanation:
We are given with the following frequency distribution below;
Age Frequency (f) X 
0 - 9 30 4.5 135
10 - 19 32 14.5 464
20 - 29 12 24.5 294
30 - 39 20 34.5 690
40 - 49 25 44.5 1112.5
50 - 59 53 54.5 2888.5
60 - 69 49 64.5 3160.5
70 - 79 13 74.5 968.5
80 - 89 <u> 8 </u> 84.5 <u> 676 </u>
Total <u> 242 </u> <u> 10389 </u>
Now, the mean of the frequency distribution is given by the following formula;
Mean =
=
= 42.9 ≈ 43 approx.
Hence, the mean age of the frequency distribution for the ages of the residents of a town is 43 years.
-9-(12-3x)=-9-1*(12)-1*(-3)=-9-12+3x=-21+3x=3(x-7)

Actually Welcome to the Concept of the Similarities.
Since here, first figure is a Triangle, hence similarity of a triangle is given by ratio of it sides and make them equate,
hence for,
1.) 16/12 = x/9 ===> 4/3 = x/9 ===> x = 9*4/3 ==> x = 36/3
hence the value of x is 12 , ===> x = 12 .
2.) here,in the case of a Reactangle the relation is such that, length = 2* breadth,
hence we apply the relation,
x = 2*4.5 ===> x = 9 units.
Y=10x+1
x=-1→y=10(-1)+1=-10+1→y=-9
x=0→y=10(0)+1=0+1→y=1
x=1→y=10(1)+1=10+1→y=11
x=5→y=10(5)+1=50+1→y=51
x y
-1 -9
0 1
1 11
5 51