So it gives you the "= 210" part of it so you just need to figure out how to write "40% of a number is added to the number"
the questions already tells you that "the number" is "x"
so that means "40% of x is added to x" instead of writing "add" you can replace it with a plus sign "+" (40% of x) + x another way to write 40% of x is 0.40x so your equation is .4x + x = 210
