please help answer this!!!

Answer:
49) [tex]12\,b^4[/tex]
50) [tex]200\,x^6[/tex]
Step-by-step explanation:
Use the properties of exponent to reduce this expressions:
a) [tex]3\,b\,*\,4 \,b^3=(3\,*\,4)\,(b\,*\,b^3)=12\,b^{(1+3)}=12\,b^4[/tex]
b) [tex]5\,x^2\,*\,8\,x\,5\,*\,x^3=(5\,*\,8\,*\,5)\,(x^2\,*\,x\,*\,x^3)=200\,x^{(2+1+3)}= 200\,x^6[/tex]