$\cos\left(\frac{14\pi}{15}\right)\cos\left(\frac{23\pi}{30}\right)+\sin\left(\frac{14\pi}{15}\right)\sin\left(\frac{23\pi}{30}\right)$

$25=3\left(x+7\right)-5x$

$\int2x\tan\left(x\right)\sec^2\left(x\right)dx$

$2x^2+3x-x^2-x$

$8z-4-6z-1$

$\left(4x^2+3b\right)^2$

$3\left(1.4a+8.9b\right)-8.3\left(ab\right)$