So we have the system of equations:

equation (1)

equation (2)
To use substitution, we are going to solve for one variable in one of our equations, and then we are going to replace that value in the other equation:
Solving for

in equation (2):



equation (3)
Replacing equation (3) in equation (1):






equation (4)
Replacing equation (4) in equation (3):



We can conclude that the solution of our system of equations is <span>
(7/5, 21/10)</span>
Answer:
5 x 6
Step-by-step explanation:
The answer should be 19 if you mean 3 to the power of 2. as listed below.
First, you need to figure out hoe many boys and girls there are.
40% = 0.4
0.4 x 20 = 8 boys
20 - 8 = 12 girls
25% of the boys have glasses
0.25 x 8 = 2 boys who wear glasses
50% of the girls have glasses
0.5 x 12 = 6 girls who wear glasses
2 + 6 = 8
8 students wear glasses