Find the 8th 15th 50th and a formula for the nth term of these Arithmetic progression
a.3,7,11...
b.-5,-3 1/2,-2...
c.1/2,5/6,1 1/6,...

80 ml of the first solution and 120 ml of the second solution

Step-by-step explanation:

Let the first solution weigh x ml, let the second solution weigh 200-x ml.

The amount of acid in the first solution is x/100*50=0.5x

The amount of acid in the second one is (200-x)/100*80= 160-0.8x

The quantity of acid in the desired mixture is 200/100*68= 136

0.5x+160-0.8x= 136

0.3x=24

x=80ml of the first solution are needed

200-80=120ml - of the second solution are needed