An anion is a negatively charged ion. An element can become an anion if it takes an extra electron such that it has one more electron than protons.
Atoms would preferentially taken an extra electron so that it can have a full octet and be more stable.

are some of the few elements that would have a -1 charge.
You can establish a system of two equation with two variables.
Varibles are:
V1 = volume of the 50% sugar solution
V2 = volumen of the 80% sugar solution
Equations:
Balance of sugar:
Sugar from 50% solution: 0.5*V1
Sugar from 80% solution: 0.8*V2
Sugar in the final solution (mix): 0.6 * 105 = 63
1) 0.5V1 + 0.8V2 = 63
Final volume = volume of 50% solution + volume of 80% solution
2) V1 + V2 = 105
From (2) V1 = 105 - V2
Substitue in (1)
0.5 (105 - V2) + 0.8 V2 = 63
52.5 - 0.5V2 + 0.8V2 = 63
0.3 V2 = 63 - 52.5
0.3 V2 = 10.5
V2 = 10.5/0.3
V2 = 35mL
V1 = 105 - 35 = 70 mL
Answer: 70 mL of the 50% solution and 35 mL of the 80% solution.
Seems to be 3.6 since it’s closer by 1, As for 4.0 it would be 5 more.