Acoal car on a train weighs 30 tons plus 1 ton per cubic yard of coal x that it carries. the total weight of a coal car is: f(x) = x + 30. how will the graph of this function change if the coal car weight is changed to 26 tons? the line will shift vertically up by 4 tons. the line will shift vertically up 26 tons. the line will shift vertically down by 4 tons. the line will shift vertically down by 26 tons.