With an initial 6 dollars that must be added to whatever is bought
Y=__x+6
And lastly it’s 3.50 PER POUND and we don’t know how many pounds are bought so it must be multiplied by 3.50 because if x= say 2, then 3.50 times 2 would be the correcf expression which is why the final term should be 3.50x or 3.50(x) or 3.50•x any works well which leaves your final equation to be
Use a number line if you need 4/10 - 6/10 = -2/10a simpler way is to do the opposite 6/10 - 4/10 = 2/10 then the answer would be the opposite as well. so, -2/10