Let C = cost price; x= percent above cost price (value under the question). Then the base equation is C*(1 + 0.01x)*0.9 = C*(1 + 0.35). <<<---=== it is translation of the problem to Math. Cancel C in both sides to get (1 + 0.01x)*0.9 = 1.35. Then 1 + 0.01x == 1.5 ====> 0.01x = 1.5 - 1 = 0.5 ====> x = = = 50. ANSWER. 50%.