D. X=130 but im not sure if this is correct
HI
the answer is 200 millimeters
<333
Answer:
Step-by-step explanation:
=7 (1+11+111+1111......n)
=7/9 (9+99+999+9999....n)
=7/9 ((10-1)+(10^2-1)+(10^3-1)+....n)
=7/9 ((10+10^2+10^3...n)-(1+1+1+1.....n))
=7/9 ((10 (10^n-1)/(10-1))-n)