Question

PLS HELP!!!!!!!!!!!!!!!!!! Molly and Maddie are clothes shopping. Molly has $100.00 and a coupon for a $10.00 discount at a clothing store where each shirt costs $15.00. Molly thinks that she can buy 8 shirts, but Maddie says that Molly can buy 7 shirts. The equations they used to model the problem are listed below. Solve each equation algebraically, justify your steps, and determine who is correct and why. Molly's equation 15x + 10 = 100 Maddie's equation 15x - 10 = 100

Answer 1

Maddie is correct.

Explanation:

Give that Molly has $100.00 and a coupon for a $10.00 discount.

The cost of 1 shirt = $ 15.00

Let Molly can buy a maximum of x t-shirt.

Note that must be a counting number ( integer) as the number of t-shirts can't be a fractional number.

So, the cost of x t-shirts = $ 15x

As she has a discount coupon, so the cost she has to pay after using the discount coupon is $15x-$10, which must not be greater than the money she has, i.e $100.

So, the required inequality is

`15x-10\leq 100\cdots(i)`

As given, Molly's equation is 15x + 10 = 100 and Maddie's equation is 15x - 10 = 100.

Maddie's equation is partially correct in comparison with the equation (i) as there is a sign of equality only.

Now, solving the equation (i), we have

`15x\leq 100+10`

`x\leq (110)/(15)`

`x\leq 7 (1)/(3)`.

As x must be an integer, so the possible value of x is 7.

Hence, she can buy a maximum of t-shirts, so, Maddie is correct.