The reciprocal of any number is the other number you must multiply it by to equal one. In this case it's 9/2
$1.75
If 4 lemons altogether cost $7, you want to divide the price by 4 to find the price for one single lemon.
7/4 = $1.75
Now if you buy 4 lemons that cost $1.75, your total will add up to $7
Plugging 10 for k in the expression gives us

We simplify this expression to
251 is your answer
Unlike terms displays terms which are not the same. x+2y would be the answer.