How to find the first number of an arithmetic sequence?

Depends on what you're given but if you are given a certain term and the common difference  subtract An, the value of the sequence at that term, by (n-1*d) which is the term number -1 times the common difference. So An-((n-1)*d)

Abit confused about what you mean, but i think you might be referring to slope intercept form: y = mx + bin that case b, or the y intercept is already given.(0,-1)find the slope by using the formulay2 - y1/x2 - x1the final slope will be 4/2, equivalent to 2.now your equation should look like thisy = 4/2x -1sorry if this didn’t you out!

1200 inches = 30 yards12 inches= 1 foot3 feet= 1 yard3feet= 36 inchesyou can set up a proportion then use inverse operations that looks sorry it looks so sloppy lol