Solve each formula for N

r/n + 2 = p

t=100 (n+3)

pv/nr = T

8a + 2n + 6b

Get rid of the parenthesis.

t = 100n + 300

Subtract 100n and t from both sides.

-100n = 300 - t

Divide both sides by -100.

n = .01t - 3

This should help you with the other equations.

The last example is not an equation and therefore cannot be solved for n.