Question

Mika’s gym allows her to bring 3 guests for free. After the first three, she must pay $7 per guest. How many guests, g, can she bring to the gym if she pays $42? Three of these equations give the correct value of g. Which equation does NOT?

7g = 63
7(g – 3) = 42
7g – 3 = 42
g = 9

Answer 1

Okay. So 3 guests are free. Mika has $42 dollars she can spend with $7 per guest. 42/7 = 6. Add the 3 other guests and you get 9. Mika can bring 3 guests with her to the gym. D gives the correct answer, and A and B give out the correct equations as well. C is not right, because 7 * 9 is 63. 63 - 3 is 60. 60 > 42. C is the incorrect equation. The answer is C.

Answer 2

`7\cdot g-3 = 42`

Explanation:

As the first three guest are three and each aditional guest costs $ 7 dollars. The formula is presented as follows:

`7\cdot (g-3) = 42`

Or:

`7\cdot g = 63`

Or:

`g = 9`

The wrong equation is:

`7\cdot g-3 = 42`