Answer:
There are 18 triangles and 24 parallelograms.
Step-by-step explanation:
Let the number of Triangles be x
and number of Parallelograms be y
By given data;
There are together 42 triangles and parallelogram

Also there are 150 total sides,
Now we know that triangle have 3 side and parallelogram consist of 4 sides.
Hence the equation will become:
Now substituting value of x in above equation we get;

Hence 
Hence, there are 18 triangles and 24 parallelograms.