First term (a) = -15
common difference(d)= -9-(-15)
= -9+15=6
So,
12th term(a12)= a +(n-1)d
= -15+(12-1)×6
= -15 + 11×6
= -15+66
= 51
Explain your question more
Hi, these equations are pretty easy actually, first thing you should know when working with variables is that you always want to leave the variable alone, let's take the third excersise for example, 12x + 2 = 146. Here you just do the opposite on the other side of the equation depending if the number is positive or negative. Since x is being multiplied by 12 you first get rid of the 2, since its positive you subtract it to 146. Now the answer should be 12x = 144. Now since you're multiplying 12 to x you just divide 12 from 144, 144/12 = 12
x = 12
