Answer:
14/6
Step-by-step explanation:
Lets be a price of the calculator - $ a
then , after using the coupon, you need to pay $(a-18)
and after using 15% discount , you need to pay (1-0.15)a=0.85a
then, if
(a-18) will be more than 0.85a, you should prefer 0.15 % discount, because it will be cheaper,
a-18> 0.85a
a-0.85a>18
0.15a > 18
a>120, that means that if the price of the calculator more than $120, 15% discount is better,
but if the price of the calculator is less than $120, you should choose $ 18 coupon.
for example, we have the price of the calculator $100
100-18=82,
100*0.85 =85, coupon is better.
If the price of the calculator $200
200-18=182,
200*0.85=170, so 15% discount is better
if price of the calculator is $120,
120-18=102
120*0.85=102,
it will not matter, what you are going to use, because you are going to pay the same amount of money
1/3 + 1/3 + 1/3 + 1/3 + 1/3 + 1/3 = 6/3
