Question

integral sign from -1 to pi f(x) dx = 2/3 . find dx of integrals sign from -pi to 1 f(x)

Answer 1

would that be -2/3?

Answer 2

So you're given
\[\large\int_{-1}^\pi f(x)~dx=\frac{2}{3}\]
and you're asked to find
\[\large\int_{-\pi}^1f(x)~dx~~?\]
I'd say we don't have enough information to conclude anything.