Answer:
8 Minutes
Step-by-step explanation:
since we are trying to find how many minutes have passed we first need to find how much substance was used during the time. we can do that by subtracting the leftover substance from the amount we started with.
666-562 = 104
Now that we know how much substance was used we can then use our conversion rate (13 per minute) and find how many minutes have passed by dividing.
104 / 13 = 8
2 times a number minus 9 is less than or equal to 21. and in inequality form that’s: 2x - 9 >_ 21 and u make a number line and a closed circle on 15 and an arrow going right. i hope i understood your question right
