Ineed solving these equations and need to show work. have a quiz over arithmetic sequences tomorrow so i need to brush up on this topic a bit.

17 for the first number 3)

[you should try a couple and post on here to get it checked]

Step-by-step explanation:

First 3)

3rd ->70

10th->210

x->350  ( x represents the top rung)

Arithmetic sequences you should think equations of lines :)

So equations of lines have the same slope no matter the two points you choose on that line

Slope=(210-70)/(10-3)=140/7=20 using the points (3,70) and (10,210)

Slope=(350-210)/(x-10)=140/(x-10) using  (10,210) and (x,350)

Set the two slopes equal to each other  140/7=140/(x-10)

so 7=x-10

which means x=17

my guess is

step-by-step explanation: