Answer:
100
Step-by-step explanation:
85 +80+100+85+x(the unknown),/the number of numbers ie 5
350+x/5=90
350+x=90 * 5
350+x=450
x=450-350
x=100
Answer:1) c. 5,9,13,17,21
2) a. a1=8, an=an-1 -2
Step-by-step explanation: 1) an=4n+1
⇒ a1=4×1+1=5
a2=4×2+1=9
a3=4×3+1=13
a4=4×4+1=17
a5=4×5+1=21
2) clearly a1=8 and then the terms of series are decreasing by 2
so, an=an-1 -2
Answer:
15cm
Step-by-step explanation:
a^2+b^2=c^2
12^2+9^2=c^2
144+81=c^2
c^2=225
c=15
