when a quadratic equation isn't able to be solved using factorisation, the quadratic formula can be used, which has the general formula of ** **. The letters in the formula represent the coefficients in the quadratic equation, given in the question.
quadratic equations are written generally as: ax2 + bx + c = 0.
so, in the equation given in the question, a=3, b=-60 and c=220. You then put these values into the quadratic formula, which will give you the answer, using a calculator.