It is similar to a 90 degree angle, yet it is more obtuse than it is acute, so that narrows down to this answer: the correct answer is 95 degrees
An inverse operation is writing the opposite sign to another sign
Let
be the number of liters of the 10% solution to be used, and
the number of liters of the 4% solution. The chemist wants to end up with a 4 liter solution, so

For each liter used in the mixture, a concentration of either 10% or 4% acid will be contributed, and the goal is to make a 4L solution whose concentration is 7%, which means

Solving for
gives
, so 2L of both solutions is needed.
Answer:

Step-by-step explanation:
hope u got it.