Mark is buying black pens and blue pens. He wants to buy the same number of each. Black pens come in packs of 3, and blue pens come in packs of 4. What is the least number of each color mark can buy?

Can someone plz me understand how to do these. plz, show work.in exercises 1-4, rewrite the expression in rational exponent form.[tex]\sqrt[4]{625} \sqrt[3]{512} (\sqrt[5]{4} )³ (\sqrt[4]{15} )^{7}\\ (\sqrt[3]{27} )^{2}[/tex]