Im on the verge of tears and i️ just want to be done with this! a pharmacist wishes to mix a solution that is 8% minoxidil. she has on hand 100 ml of a 7% solution and wished to add some 10% solution to obtain the desired 8% solution. how much 10% solution should she add?

100 (.07) + x (.10) = (100+x) (.08)

Amount * percent + amount* percent = (total amount) * desired percent

distribute

7 + .1 x = 8+.08x

subtract .08x from each side

7 +.02x = 8

subtract 7 from each side

.02x =1

divide by .02

x = 1/.02

x = 50

add 50 ml of the 10% solution

50mL of 8% solution

Step-by-step explanation:

Givens

Let the number of mL of 10% solution needed = x

Let the number of mL of 7% solution to be used = 100

She needs an 8% solution.

10%*x + 100*7% = (100 + x)*8%

(10/100)*x + 100*7/100 = 100*8/100 + x*8/100   Multiply through by 100

10x + 700 = 800 + 8x                     Subtract 700 from both sides

10x + 700 - 700 = 800 - 700 + 8x

10x  = 100 + 8x                                 Subtract 8x from both sides.

10x - 8x = 100                                    Combine like terms on the left

2x = 100                                            Divide by 2

x = 100/2                                           Do the division

x = 50

You need to add 50 Ml of the 10% solution.

Check

Left Hand Side

100 mL of 7% = 7 mL of active ingredient.

50 mL of 10% = 5 mL of active ingredient

Total                   12 mL of active ingredient

Right Hand Side

150 mL of 8% = 12 mL of active ingredient

And it checks.

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this