The answer of the above equation is 36.

Explaination:

Let the blue glass be, B

Let the yellow glass be, Y

& Red glass be, R

So, arranging the above equations in the form of the above terms.

Equation (1); R + Y + B = 18

Equation (2); B + B + B = 2 Y

Equation (3); Y + Y = 2 R – B

Equation (4); R + R = 12 + B

Equation (5); 0.5(R) + [0.5(B) + Y] * B =?

Now, solving equation (2);

B + B + B = 2 Y

3B = 2Y

Blue glass, B = 2/3 (Y).

Substitute, the B in equation (3);

Y + Y = 2 R – B

2Y = 2R – B

2Y = 2R – 2/3 (Y)

Red glass, R = 4/3 (Y)

Now, substitute the value of R & B in equation (1);

R + Y + B = 18

4/3 (Y) + Y + 2/3 (Y) = 18

4Y + 3Y + 2Y = 18 * 3

Yellow glass, Y = 6,

We already have, B = 2/3 (Y) & R = 4/3 (Y) from equation (2) & (3);

B = 2/3 (Y)

B = 2/3 * 6

Blue glass, B =4

&

R = 4/3 (Y)

R = 4/3 * 6

Red glass, R = 8

For final equations, substitute the values in equation (5);

0.5(R) + [0.5(B) + Y] * B =?

0.5(8) + [0.5(4) + 6] * 4 =?

= 4 + [8] * 4

= 36

0.5(R) + [0.5(B) + Y] * B =36