Answer:
8n+12=36, triplets are 8 years old
Step-by-step explanation:
total age is 36
one of them is 12 years old so -> 36-12 = 24
three triplets so 24/3 = 8
there are three 8 years olds and one 12 year old. n = 3
C is the correct answer. Vertical angles.
Answer:
The chemist needs to add 400mL of 40% solution.
Step-by-step explanation:
The equation
gives the percent concentration 
of the final mixture, when 
mL of the 40% solution are added.
Now we are asked, how many milliliters of the 40% solution should the chemist add to get final percent concentration 
; this is just a matter of solving the equation
and we solve it the following way:
Thus, the chemist needs 400mL of 40% solution to get 30% concentration of the final mixture.
Answer:
add 21 five times
Step-by-step explanation:
