11. these calculations all seem off. where is my mistake?

Pierce Manufacturing determines that the daily revenue, In dollars, from the sale of x lawn chairs is R(x) = 0.007x +0.02x +0.4x. Currently, Pierce sells 60 lawn chairs daily. a) What is the current daily revenue? bj How much would revenue increase if 64 lawn chairs were sold each day? c) What is the marginal revenue when 60 lawn chairs are sold daily? d) Use the answer from part (c) to estimate R(61), R(62), and R(63). a) The current revenue is $ 61 bj The revenue would increase by $ 4 85 (Round to the nearest cert.) c) The marginal revenue is $ 66 when 60 lawn chairs are sold daily. 4