Question 619474
I'll do the first one to get you started. Post the other question if you still need help with it.


# 1


Let x = amount of 10% solution and y = amount of 25% solution


We want our final solution to be 300 L, so x+y = 300. Solve this for y to get y = 300 - x



Since you have x liters of the 10% solution, you have exactly 0.1x liters of acid. Similarly, since you have y liters of the 25% solution, you have exactly 0.25y liters of acid



In total, you have 0.1x+0.25y liters of pure acid. We want our final solution to be 15% acid, so there must be 300*0.15 = 45 liters of pure acid in the final solution (mixed with water and other chemicals)


So we can say 0.1x+0.25y = 45



0.1x+0.25y = 45


0.1x+0.25(300 - x) = 45


0.1x+0.25(300) - 0.25x = 45


0.1x + 75 - 0.25x = 45


-0.15x + 75 = 45


-0.15x = 45 - 75


-0.15x = -30


x = -30/(-0.15)


x = 200


So you need <font color="red">200 liters</font> of the 10% solution


Now plug x = 200 into y = 300 - x to get



y = 300 - x


y = 300 - 200


y = 100


and you need <font color="red">100 liters</font> of the 25% solution