How much pure antifreeze must be added to 12 gallons of 20 a

How much pure antifreeze must be added to 12 gallons of 20% antifreeze to make a 40% antifreeze solution?

Select one: a. 2 gallons b. 4 gallons c. 6 gallons d. 8 gallons

and

Select one:

b. 4 gallons

solution

12 gallons of solution contains 20% of antifreeze i.e. 2.4 gallons of antifreeze

If x gallons of antifreeze is added then

Total solution is 12+x gallons and

Total antifreeze = 2.4+x. This is 40% of total solution

(2.4+x)/(12+x) = 0.4

2.4 + x = 4.8 + 0,4x

x-0.4x = 4.8 - 2.4

0.6x = 2.4

x = 2.4 / 0.6 = 4

so 4 gallons of antifreeze should be added to make it 40%.

The answer is b.

| x+6| = 2x + 5

since the values in a,b,c,d are not visible pl find solution below.

Let us first solve x + 6 = 2x + 5

x = 1

Since it is |x+6| we have to solve

-(x+6) = 2x + 5

-x - 6 = 2x + 5

-3x = 11

x = -11/3

Solutions are x = 1, x = -11/3