lets write the equations with shortcodes A for apple, L for lemon, W for watermelon and T for tomato

3A = 30 => A = 10

2L + A = 40 => 2L = 40 -A = 30 => L = 15

from 4th T + T^2 = 12 => T => T(1+T) = 12 => T = 3

from 3rd T + 2W => 24 => 2W = 24 – T = 21 => W = 21/2

the last one

W + L*T => 21/2 + 15*3 => 10.5 + 45 => 55.5

 

This is following this pattern

A*B – (B-A) – 1
for first line 4*6 – (6-4) -1 => 24 – 2 -1 => 21
you can see the same for all other lines, thus for the last one

4*4 – (4-4) – 1 => 15

You can not get individual item’s value as there are only 3 equations and more than 3 variables.

however you can get the value by doing
Eq3 – Eq2 + Eq1
thus the answer will be 27 – 24 + 21 => 24

Let’s quickly write the equations

B1 + B2 = 14

B1 + B3 = 15

B2 + B4 = 16

B3 – B4 = 10

by adding all equations

B1 + B2 + B3 = (14 + 15 + 16 + 10 )/2 = 55/2 = 27.5

B3 = 27.5 – (B1 + B2) = 27.5 – 14 = 13.5 => B3 = 13.5

B2 = 27.5 – (B1 +B3) = 27.5 – 15 = 12.5 => B2 = 12.5

B1 = 14 – B2 = 14 – 12.5 = 1.5 => B1 = 1.5

B4 = B3 – 10 = 13.5 – 10 = 3.5 => B4 = 3.5

 

Lets say B is half full blue glass, Y is half full yellow glass and R is half full red glass, then

2B + B + 2B = 15 => 5B = 15 => B = 3

2Y – Y + 2B = 10 => Y + 2*3 = 10 => Y = 4

2R + 2R – R = 6 => 3R = 6 => R = 2

Now

B + (B+R)*Y = 3 + (3+2)*4 => 3 + 20 => 23