an=a+(n-1)d

Solution for an=a+(n-1)d equation:

Simplifying
an = a + (n + -1) * d

Reorder the terms:
an = a + (-1 + n) * d

Reorder the terms for easier multiplication:
an = a + d(-1 + n)
an = a + (-1 * d + n * d)
an = a + (-1d + dn)

Solving
an = a + -1d + dn

Solving for variable 'a'.

Move all terms containing a to the left, all other terms to the right.

Add '-1a' to each side of the equation.
-1a + an = a + -1d + -1a + dn

Reorder the terms:
-1a + an = a + -1a + -1d + dn

Combine like terms: a + -1a = 0
-1a + an = 0 + -1d + dn
-1a + an = -1d + dn

Reorder the terms:
-1a + an + d + -1dn = -1d + d + dn + -1dn

Combine like terms: -1d + d = 0
-1a + an + d + -1dn = 0 + dn + -1dn
-1a + an + d + -1dn = dn + -1dn

Combine like terms: dn + -1dn = 0
-1a + an + d + -1dn = 0

The solution to this equation could not be determined.