Four milliliters of ink a is added to 10 milliliters of ink b, forming a mixture of inks. ink a contains 10% blue pigment. ink b contains an unknown percentage of blue pigment. the mixture of the two inks contains 35% blue pigment.

what percentage of blue pigment is in the mixture of the two inks?

45%
49%
60%
75%

The answer is 45%

1. Calculate how many ml of blue pigment are in 4ml of ink A if it contains 10% blue pigment:
4 ml is 100%
a ml = 10%
4 ml : 100% = a : 10%
a = 4 ml * 10% : 100% = 0.4 ml

2. Calculate how many ml of blue pigment are in 10ml of ink A if it contains x% blue pigment:
10 ml is 100%
b ml = x%
10 ml : 100% = b : x%
b = 10 ml * x% : 100% = x/10 ml

3. 2. Calculate how many ml of blue pigment are in 14ml (because Four milliliters of ink A is added to 10 milliliters of ink B) of total mixture if it contains 35% blue pigment:
14 ml is 100%
t ml = 35%
14 ml : 100% = t : 35%
t = 14 ml * 35% : 100% = 4.9 ml

4. What percentage of blue pigment is in the mixture of the two inks:
a + b = t
0.4 + x/10 = 4.9
x/10 = 4.9 - 0.4
x/10 = 4.5
x = 4.5 * 10 = 45