You need a 60% alcohol solution. On hand, you have a 480 mL of a 75% alcohol mixture. How much pure water will you need to add to obtain the desired solution?​

120 mL

Step-by-step explanation:

If the 480 mL has 75% concentration, then 360 mL are alcohol. To turn the 360 into only 60%, you need to increase the amount of water.

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!