$760mm Hg = 1 atm$ $760 \div 1 \times 4.8 \div x$ $= 3648 mm Hg$
Work Step by Step
Since you are trying to find how many mmhg equals 4.8atm you will need to keep in mind $760mmhg=1atm$. You use stoichiometry by cross canceling out certain variables. Therefore, you place 760 mm hg over one and place 4.8 over x then multiply so the atm are diagonal from each other they and will cancel out. Multiply what is left and you get 3648 mm hg.