help, i know the answer but i don’t know how to do the work

Answer:CStep-by-step explanation:Using the rule of radicals[tex]\sqrt{a}[/tex] × [tex]\sqrt{b}[/tex] ⇔ [tex]\sqrt{ab}[/tex]Simplifying each radical before combining them.[tex]\sqrt{45t}[/tex]= [tex]\sqrt{9(5t)}[/tex] = [tex]\sqrt{9}[/tex] × [tex]\sqrt{5t}[/tex] = 3[tex]\sqrt{5t}[/tex]-----------------------------------------------------------------------------[tex]\sqrt{125t}[/tex]= [tex]\sqrt{25(5t)}[/tex]= [tex]\sqrt{25}[/tex] × [tex]\sqrt{5t}[/tex] = 5[tex]\sqrt{5t}[/tex]---------------------------------------------------------------------------Hence2(3[tex]\sqrt{5t}[/tex]) - 3(5[tex]\sqrt{5t}[/tex]= 6[tex]\sqrt{5t}[/tex] - 15[tex]\sqrt{5t}[/tex]= - 9[tex]\sqrt{5t}[/tex] → C