Find out

Remember that

step 1
Find out the cosine of angle alpha
the angle alpha lies on the II quadrant
the value of the cosine of angle alpha is negative
Remember that

substitute

Find out the tangent of angle alpha

step 2
Find out the value of the sine of the angle beta
The angle beta lies on the III quadrant
so
The value of the sine is negative
Remember that

substitute

Find out the value of the tangent of the angle beta

step 3
Find out

substitute given values


simplify
The answer is -16/33