The formula of linear equation is:

Where
x1 and x2: x coordinates(-1 and 3)
y1 and y2: y coordinates(-2 and 10)
m is the slope
We can then choose a point from the line to find the eqaution.
We need to first find the slope:

In this case:

In this case, as the y2 is given as 1,put (-1,-2) , and the slope(3 )into the eqaution :
y-(-2) = 3(x-(-1))
y+2 = 3(x+1)
Therefore

is the answer.
Hope it helps!
A numerical expression contains numbers and operations. An algebraic expression is almost exactly the same except it also contains variables.
It is 7
2*2x = 4x + 2 = 30
4x = 28
x = 7